Top 20 Kotlin Development Companies in USA (2026): Two Phones, One Language and the Play Store Deadline

Kotlin has a clear reputation as the language of Android, and Google has called Android development Kotlin-first since 2019 (Android Developers). The firms on this Top 20 Kotlin Development Companies in USA list sell something broader. Fifteen of the twenty list React Native in their published framework split and twelve list Flutter, and the median firm puts Kotlin at 17.5 percent of its languages (Clutch profiles). Across 199 reviews on the first page of their profiles, two name Kotlin, both at Orangesoft, and none mentions Kotlin Multiplatform. In a country where iOS runs 60.7 percent of mobile devices (StatCounter), most of these firms build for both phones, and Kotlin is one of several tools they reach for.

We think that changes the brief more than the shortlist.

This guide prices the work and sets out how to shortlist. It then covers what arrives after launch: the Google Play deadline that moves every August, the signing keys and store accounts that must be in your name, and the clauses that decide how you leave.

Key takeaways

• 31 August 2026 was the date from which new apps and app updates must target Android 16 (API level 36) to be submitted to Google Play (Android Developers).
• 3 December 2027 is the end of support for Kotlin 2.4, released on 3 June 2026; Kotlin 2.5 is planned for December 2026 (Kotlin).
• 60.7% of US mobile devices ran iOS in August 2026, against 39.3% for Android (StatCounter).
• 11.5% of professional developers used Kotlin in 2025, against 29.6% for Java and 5.7% for Swift (Stack Overflow).
• 2 of 199 first-page reviews across the top twenty firms name Kotlin, and none mentions Kotlin Multiplatform (Clutch profiles).
• 12% is the median Kotlin share across all 791 firms in Clutch’s US Kotlin directory; only 11 put it at half or more, and 8 of those have no reviews (Clutch).
• $115,000 to $139,972 is the spread between PayScale’s average for the Kotlin skill and Indeed’s average for Android developers (PayScale; Indeed).
• 20% less likely to crash: Google’s figure for Android apps that contain Kotlin code (Android Developers).

Kotlin in 2026: Android’s default, and a road into iOS

Kotlin is the default for Android, not the most used language. In Stack Overflow’s 2025 survey, 11.5 percent of professional developers had used Kotlin in the past year, against 29.6 percent for Java, 6.1 percent for Dart, the language behind Flutter, and 5.7 percent for Swift (Stack Overflow Developer Survey 2025). Much of the Java figure is server work, and Kotlin runs there too.

Google announced at I/O 2019 that Android development would be increasingly Kotlin-first. It reports that Android apps containing Kotlin code are 20 percent less likely to crash, and that Kotlin is fully interoperable with Java, so a team can add as little or as much Kotlin to a Java app as it wants (Android Developers). Jetpack Compose, the Kotlin UI toolkit, is Android’s recommended way to build native screens (Android Developers).

Kotlin now reaches iOS too. Kotlin Multiplatform shares code across platforms, and its core is Stable on Android, iOS, desktop and server, with web on Kotlin/Wasm still in Beta (Kotlin). Compose Multiplatform for iOS, which shares the UI as well as the logic, was declared stable and production-ready on 6 May 2025 (JetBrains).

That matters in the US because the iPhone is the majority. StatCounter put iOS at 60.7 percent of US mobile devices in August 2026 and Android at 39.3 percent (StatCounter). An Android-only Kotlin app reaches the smaller share of American users.

Two calendars run the work. Kotlin itself ships a language release about twice a year. Kotlin 2.4 arrived on 3 June 2026 and is supported until 3 December 2027, its latest tooling release 2.4.20 shipped on 7 September 2026, and 2.5.0 is planned for December 2026 (Kotlin). Google Play moves separately: since 31 August 2026, new apps and updates must target Android 16, API level 36, and existing apps must target at least Android 15 to stay available to new users on newer devices (Android Developers).

So a Kotlin brief needs three answers before any firm is compared: whether the app is Android-only or must also ship on iPhone, whether iOS should come from Kotlin Multiplatform, Swift or a cross-platform framework, and whether the app already meets the current Play target.

What Kotlin development costs in the US

Pay figures for the same kind of engineer spread by $24,972 across three sources.

PayScale reports an average base salary of $115,000 for the Kotlin skill, from 504 people, updated 1 June 2026 (PayScale). The Bureau of Labor Statistics puts the median software developer at $135,980 in May 2025 (BLS). Indeed reports $139,972 for an Android developer, from 1,100 job-posting salaries, updated 19 September 2026 (Indeed).

Only PayScale reports a Kotlin figure, and it is self-reported base pay. BLS covers all software developers, and Indeed reads advertised pay from job postings, which runs higher. The spread is a reason to ask what a vendor’s rate assumes about seniority, not a reason to pick one number.

Agency pricing on this list sits lower than on most BS23 technology lists. Seven of the twenty firms publish a $25 to $49 band, seven publish $50 to $99, and only four publish $100 an hour or more; two do not publish a rate. The median minimum project is $25,000, from $5,000 to $75,000 (Clutch profiles, read 28 September 2026). Fourteen report a most common project under $50,000.

The typical engagement on this list is a mobile app build under $50,000. The outliers are Dualboot Partners, whose most common project is $200,000 to $999,999, and Jalasoft, whose most common project is over $1,000,000. Eight factors decide where a Kotlin quote lands.

The platform decision comes first: Android only, or Android and iOS. Then the iOS approach, since Kotlin Multiplatform, native Swift and Flutter or React Native price differently; the starting point, a new app or an existing Java or older Kotlin codebase; the UI toolkit, Compose or legacy XML views; the back end; integrations such as payments, maps and health data; device and test coverage; and the support terms. Ask every vendor to price the iOS side and any migration separately.

The Top 20 Kotlin Development Companies in USA, compared

We used Clutch’s directory of Kotlin developers in the United States, sorted by Clutch Rank and read on 28 September 2026. It lists 791 firms and had no paid rows at the top of the list that day. Firms 2 to 21 below are its top 20 in Clutch Rank order.

Brain Station 23 is placed first because we publish this article. We are US-headquartered, and Kotlin is 7 percent of our published Clutch languages, but Clutch’s ranking did not place us in its top 20 and we are not claiming it did.

Every overall rating below sits between 4.7 and 5.0, so the stars do not separate these firms. The Kotlin Focus column does: Kotlin’s share of each firm’s published language split, with the cross-platform frameworks it lists.

#	Company	Best For	Team Size	Kotlin Focus	Key Tech Stack	Industries Served	Locations
1	Brain Station 23 — brainstation-23.com	Adding Android and Kotlin engineers to an in-house team	250 – 999	Kotlin 7% of languages; Flutter 15% of frameworks	Java, Spring, Kotlin, Flutter, .NET, Python	Retail, medical, telecoms, education, financial services	Springfield VA; Bangladesh, UAE, England, Malaysia, Germany
2	Suffescom Solutions — suffescom.com	Fintech and healthcare apps at offshore rates	250 – 999	Kotlin 20%, its largest language	Kotlin, Python, React Native, Next.js, Node.js	Financial services, medical, real estate, e-commerce	New York, Wilmington, Middletown DE; Mohali, Dubai, London, Sydney
3	Synergy Labs — synergylabs.co	Small businesses wanting a cross-platform app	50 – 249	Kotlin 30%, Swift 30%; Flutter 50%	Flutter, React Native, Kotlin, Swift	Ten sectors at 10%, incl. finance, government, real estate	Hollywood FL, Miami, New York, Austin, San Francisco, Chicago; Dubai
4	Excellent Webworld — excellentwebworld.com	Mid-market and enterprise builds at offshore rates	250 – 999	Kotlin 30%, PHP 30%	Kotlin, PHP, ASP.NET, Angular, Flutter, React Native	Medical, e-commerce, automotive, government	Lakeville MN, South Jordan UT; Ahmedabad, Hong Kong, Dammam, Dubai
5	CitrusBits — citrusbits.com	Enterprise mobile and AR apps with a native focus	50 – 249	Kotlin 55%, the highest here	Kotlin, Swift, Objective-C, Flutter, React	Business services, consumer, government, IT, medical	Los Angeles, Pasadena, Pleasanton, San Francisco
6	UplineSoft — uplinesoft.com	Adding low-cost engineers across many stacks	250 – 999	Kotlin 15%; React Native 46%	React Native, Ruby on Rails, Flutter, Kotlin, Java	IT, financial services, e-commerce, consumer	New York
7	Bolder Apps — bolderapps.com	Early-stage founders wanting a fast first app	50 – 249	Kotlin 30%, Swift 30%; Flutter 50%	Flutter, React Native, Kotlin, Swift	Business services, consumer, education, finance, government	Miami, New York, Philadelphia, Las Vegas, Pittsburgh, San Francisco, Salt Lake City
8	Agency Partner Interactive — agencypartner.com	Healthcare and education apps delivered in small phases	50 – 249	Kotlin 10%	React, Flutter, React Native, Kotlin, Swift	Medical, education, e-commerce, non-profit	Plano TX
9	Designli — designli.co	Non-technical founders who need a product process	50 – 249	Kotlin 10%; React Native 35%	React Native, React, Node.js, Swift, Kotlin	Consumer, construction, education, energy, finance	Greenville SC, San Francisco, Dallas; Buenos Aires, Mexico City
10	Dualboot Partners — dualbootpartners.com	Large custom software and AI programmes	250 – 999	Kotlin 10%, one of ten languages	React Native, Ruby on Rails, .NET, Flutter, Kotlin	Financial services, manufacturing, medical, construction	Charlotte NC; Montevideo
11	Orangesoft — orangesoft.co	Healthcare apps on Android and iOS	50 – 249	Kotlin 25%, Swift 25%	Kotlin, Swift, React, Next.js, Flutter	Medical, financial services	San Francisco
12	Saritasa — saritasa.com	Complex custom and AR/VR builds with six-figure budgets	50 – 249	Kotlin 10%	.NET, Django, Kotlin, Swift, Angular	Automotive, legal, manufacturing, medical	Irvine, Manhattan Beach CA, Tampa
13	Wve Labs — wvelabs.com	Mid-market app builds with an AI line	50 – 249	Kotlin 20%, Swift 37%	Swift, Kotlin, Node.js, Flutter, Laravel	Medical, real estate, arts, consumer, government	Costa Mesa, Beverly Hills CA, Miami, Dallas; Riyadh
14	Trango Tech — trangotech.com	Broad mobile and enterprise work at offshore rates	250 – 999	Kotlin 10%, one of ten languages	Kotlin, Swift, Java, .NET, React Native	Ten sectors at 10%, incl. automotive, gaming, retail	Salt Lake City, Chicago; Riyadh
15	Simpalm — simpalm.com	Education, health and nonprofit apps near Washington	10 – 49	Kotlin 21%, Swift 21%	PHP, Kotlin, Swift, React, React Native	Education, financial services, medical, non-profit	Rockville MD, Chicago, Tysons VA, Washington DC, New York
16	MMC Global — mmcgbl.com	Enterprises combining mobile, AI and blockchain work	250 – 999	Kotlin 11%	Next.js, React, Vue.js, Python, Kotlin	Real estate, education, hospitality, automotive	Austin; Dubai, Abu Dhabi
17	AppVerticals — appverticals.com	Small, fast mobile projects at offshore rates	50 – 249	Kotlin 20%	Flutter, React, React Native, Kotlin, Objective-C	Automotive, consumer, education, finance, medical	Dallas, Houston, Miami, Brewster NY; Dubai
18	Jalasoft — jalasoft.com	Large programmes staffed from Latin America	1,000 – 9,999	Kotlin 15%, Swift 15%	Angular, React, Node.js, Kotlin, Swift, C#	Business services, consumer, energy, finance, IT	Houston; La Paz
19	X-Team — x-team.com	Enterprises adding remote engineers to existing teams	250 – 999	Kotlin 15%, Go 30%	React, Node.js, Go, Kotlin, .NET	IT, gaming, financial services, media	Austin; Hawthorn East, Australia
20	AppIt Ventures — appitventures.com	Mid-market mobile products from a Denver team	10 – 49	Kotlin 15%, its largest language	React Native, Angular, Kotlin, Java, Swift	Business services, consumer, medical, education	Denver
21	EitBiz — eitbiz.com	Mobile apps and ongoing support at offshore rates	50 – 249	Kotlin 25%, Swift 40%	Swift, Kotlin, React Native, Laravel, Node.js	IT, education, financial services, medical	Fort Wayne IN; Delhi

Team sizes, service, framework and language splits, industries and locations are from each firm’s published Clutch profile, read 28 September 2026. “Best For” is our reading of that data. Engagement models and certifications are not published consistently across these profiles, so we have left them out rather than guess.

Profiles are grouped by buyer type, and the numbers match the table. Each caution comes from the Review Highlights that Clutch publishes from the firm’s verified reviews, or from its lowest sub-score where Clutch surfaced no complaint. Certifications are self-published and unverified by us. Where we cite reviews, we read the first page of reviews on each profile, up to eleven per firm.

1. Brain Station 23

We publish this article and placed ourselves first, so read this entry as the publisher’s pick. Kotlin is 7 percent of our published Clutch languages and Flutter 15 percent of our frameworks, so we are a broad engineering firm rather than a Kotlin boutique. Our strength is staffing: 60 percent of our work is engineers embedded in client teams, at the $25 to $49 band that Suffescom, Excellent Webworld and Trango Tech also publish, with a $10,000 minimum. That suits a company that owns an Android app and needs more engineers to meet the Play target, move to Kotlin 2.4 or add a shared module for iOS. Three of our eleven first-page reviews mention Android, and none names Kotlin. Our ISO 27001 and SOC 2 Type II controls matter when engineers hold your signing keys. Reviewers score Quality at 5.0, and some asked for tighter internal coordination.

For mobile app studios

3. Synergy Labs

Mobile is 60 percent of Synergy Labs’ services, and its frameworks are Flutter at 50 percent and React Native at 40, with Kotlin and Swift at 30 percent each of its languages. Seventy percent of its clients are small businesses. It publishes a $50 to $99 band with a $25,000 minimum and carries the Clutch Guarantee. Clutch’s review summary is mixed: some clients praised app quality, while others reported non-functional apps and poor architecture. Its service, framework and language splits match Bolder Apps’ exactly.

5. CitrusBits

CitrusBits has the highest Kotlin share here, at 55 percent of its languages, and is the only firm above half. AR and VR make up 30 percent of its services, and 40 percent of its clients are enterprises. It publishes a $100 to $149 band with a $50,000 minimum, and its most common project runs $50,000 to $199,999. Four of its first-page reviews mention Android. Cost is its lowest sub-score at 4.8 across 36 reviews, and Clutch surfaced no recurring complaint.

7. Bolder Apps

Bolder Apps publishes the same splits as Synergy Labs: mobile at 60 percent of services, Flutter at 50 percent of frameworks, and Kotlin and Swift at 30 percent each of languages. It lists seven US offices, publishes a $50 to $99 band with a $5,000 minimum, and carries the Clutch Guarantee. Six reviews average 5.0, the thinnest record on this list, so its rating says less than most. Ask who will build your app and where.

9. Designli

Designli is a JavaScript shop that ships mobile apps: JavaScript is 55 percent of its languages, React Native and Node.js 35 percent each of its frameworks, and Kotlin 10 percent. Clutch highlights its SolutionLab discovery process for clients without technical staff. It publishes a $50 to $99 band with a $10,000 minimum and builds from Greenville, San Francisco, Dallas, Buenos Aires and Mexico City. Cost is its lowest sub-score at 4.8 across 83 reviews, with no recurring complaint.

11. Orangesoft

Orangesoft is the only firm here whose first-page reviews name Kotlin, in two of eleven, and seven of its reviews mention Android. Kotlin and Swift are 25 percent each of its languages, and medical work is 90 percent of its industries, the most concentrated focus on this list. It publishes a $50 to $99 band with a $25,000 minimum. Clutch lists San Francisco, where 1 percent of its staff work. Some reviews were dissatisfied with the quality of design work.

13. Wve Labs

Swift leads Wve Labs’ languages at 37 percent, with Kotlin at 20, and mobile is half its services. It publishes a $50 to $99 band with a $25,000 minimum, and lists Costa Mesa, Beverly Hills, Miami, Dallas and Riyadh. Its sub-scores run from 4.9 to 5.0 across 33 reviews, and Cost scores 5.0. Some clients found that initial feature implementation did not fully match their vision.

15. Simpalm

Simpalm’s languages are PHP at 26 percent and Kotlin and Swift at 21 percent each, and mobile is 40 percent of its services. Education, finance, medical and nonprofit work are 20 percent each of its industries. It does not publish a rate, has a $10,000 minimum, and lists Rockville, Tysons, Washington, Chicago and New York. All four sub-scores are 4.9 across 64 reviews. Some clients reported occasional delays in receiving updates.

20. AppIt Ventures

Kotlin is AppIt Ventures’ largest language at 15 percent, in a split of eleven, and React Native leads its frameworks at 30. Mobile is half its services. It publishes a $100 to $149 band with a $25,000 minimum, and its most common project runs $50,000 to $199,999. Five first-page reviews mention Android. Sub-scores run 4.8 to 4.9 across 39 reviews. Some clients suggested clearer scope definitions at the outset to avoid misunderstandings.

21. EitBiz

Swift is 40 percent of EitBiz’s languages and Kotlin 25, and application management and support is 15 percent of its services, useful after launch. It publishes a $25 to $49 band with a $5,000 minimum, and lists Fort Wayne, Indiana and Delhi. Its most common project is $10,000 to $49,999. Sub-scores run 4.8 to 4.9 across 34 reviews. Some clients wanted more proactive design suggestions.

For larger teams and offshore rates

2. Suffescom Solutions

Suffescom holds first place in Clutch’s Kotlin ranking, and Kotlin is its largest language at 20 percent. Mobile and web are 40 percent each of its services, and finance and medical work 35 percent each of its industries. It publishes a $25 to $49 band with a $25,000 minimum and has 121 reviews, the most on this list. All four sub-scores are 4.9. Some clients noted that it delivers to specification but offers little creative input.

4. Excellent Webworld

Kotlin and PHP are 30 percent each of Excellent Webworld’s languages, and it spreads nine frameworks at 11 or 12 percent. Its clients split evenly across enterprise, mid-market and small business. It publishes a $25 to $49 band with a $25,000 minimum and lists Lakeville, Minnesota and South Jordan, Utah, with offices in Ahmedabad, Hong Kong, Dammam and Dubai. Some clients wanted more thorough quality assurance after finding bugs.

6. UplineSoft

UplineSoft splits its work between custom software at 60 percent and staff augmentation at 40, and its framework split leads with React Native at 46 percent. Kotlin is 15 percent of its languages. It publishes a $25 to $49 band with a $5,000 minimum, and Clutch notes that 12 percent of its staff work in its New York office. All four sub-scores are 5.0 across 70 reviews. Some clients noted initial onboarding challenges.

14. Trango Tech

Trango Tech splits its languages across ten at 10 percent each, Kotlin and Swift among them, and mobile is 40 percent of its services, including wearable apps. It publishes a $25 to $49 band and no minimum, and lists Salt Lake City, Chicago and Riyadh. Its sub-scores are the lowest here, from 4.5 to 4.6 across 30 reviews. Some clients asked for faster minor updates, more detailed documentation and more frequent early check-ins.

16. MMC Global

MMC Global splits its services evenly across custom software, blockchain, generative AI and mobile at 20 percent each. Python leads its languages at 21 percent, and Kotlin is 11. Forty percent of its clients are enterprises. It publishes a $50 to $99 band with a $25,000 minimum and lists Austin, Dubai and Abu Dhabi. All four sub-scores are 4.8 across 35 reviews, and Clutch surfaced no recurring complaint.

17. AppVerticals

Mobile is 40 percent of AppVerticals’ services, and Flutter leads its frameworks at 30 percent, with Kotlin at 20 percent of its languages. It publishes a $25 to $49 band with a $25,000 minimum, yet its most common project is under $10,000. It lists Dallas, Houston, Miami, Brewster, New York and Dubai. Sub-scores run 4.7 to 4.8 across 29 reviews. Some clients mentioned occasional communication challenges.

18. Jalasoft

Jalasoft is the largest firm here, and its most common project is over $1,000,000. Kotlin and Swift are 15 percent each of its languages, and Clutch notes 38 percent of its staff work in Houston, with delivery from La Paz. It publishes a $25 to $49 band with a $50,000 minimum. Seven reviews is a thin record, and Cost is its lowest sub-score at 4.4. Some clients noted language barriers, as English is a second language for many of its staff.

19. X-Team

X-Team is a staff augmentation firm first: augmentation is 40 percent of its services, and 60 percent of its clients are enterprises. Go leads its languages at 30 percent, and Kotlin is 15. It publishes a $50 to $99 band with a $25,000 minimum, and Clutch lists Austin and Hawthorn East, Australia. Eight reviews is a thin record, which makes its 4.9 rating hard to weigh. Cost is its lowest sub-score at 4.6.

For custom software firms with a mobile line

8. Agency Partner Interactive

Agency Partner Interactive lists nine frameworks at 10 to 20 percent each, and Kotlin is 10 percent of its languages. Custom software and mobile make up 65 percent of its services, and medical work 40 percent of its industries. Its most common project size across 86 reviews is under $10,000, which points to work bought in small phases. Clutch notes it could improve in keeping communication consistent and adhering to schedules.

10. Dualboot Partners

Dualboot Partners publishes a $75,000 minimum, the highest here, and does not publish a rate. Kotlin is one of ten languages at 10 percent each, and AI consulting and development make up 35 percent of its services. It builds from Charlotte and Montevideo. Its most common project is $200,000 to $999,999, and Cost is its lowest sub-score at 4.7 across 56 reviews. Clutch notes a better upfront understanding of scope could improve its estimates.

12. Saritasa

Kotlin and Swift are 10 percent each of Saritasa’s languages, and mobile is 10 percent of its services, so it suits a larger system that includes an app more than an app on its own. AR and VR make up 30 percent of its services. It publishes a $100 to $149 band with a $50,000 minimum. Its 106 reviews are the second most on the list, with Cost lowest at 4.6. Some clients experienced delays and budget overruns from scope changes.

What the twenty profiles show

Kotlin is a minority share at most of these firms. Kotlin’s share of the twenty firms’ published language splits has a median of 17.5 percent, and six put it at 10 or 11 percent. Only CitrusBits puts it above half. It is still the largest or joint-largest language at eleven of the twenty, two of them in ten-way ties, because many firms spread their languages thinly (Brain Station 23 analysis of Clutch profiles, read 28 September 2026).

The whole directory has a thin top. Across all 791 US firms, the median puts Kotlin at 12 percent, and 347 firms put it at 10 percent or less. Only 11 put it at half or more, 8 of those have no reviews, and 289 firms in the directory have no reviews at all. A Top 20 Kotlin Development Companies in USA list built on ratings will always favour broad mobile agencies over small Kotlin specialists.

These firms sell both phones. Seventeen of the twenty list Swift beside Kotlin, fifteen list React Native and twelve list Flutter. Nine list Java. For a buyer, that means the firm will often propose a cross-platform framework unless you ask for native Kotlin, and the proposal should say why.

The reviews describe apps, not languages. Of 199 first-page reviews, two name Kotlin, both at Orangesoft, and none mentions Kotlin Multiplatform. Forty-six mention Android and fifty mention iOS or the iPhone. Clients describe launches, deadlines and communication, so the Kotlin evidence has to come from code, architecture documents and apps you can install.

Cost is the weak sub-score again. Among the 14 firms whose sub-scores differ, Cost is the lowest or joint lowest for 12. Three firms have fewer than ten reviews: Bolder Apps with six, Jalasoft with seven and X-Team with eight. Synergy Labs and Bolder Apps publish identical service, framework and language splits, which is worth a question if both reach your shortlist.

How to shortlist a Kotlin development company

Order the filters so the first one removes the most firms.

Step 1: Decide the platforms. Android only, or Android and iPhone. In the US, iOS is the majority of devices, so most briefs need both.

Step 2: Decide the iOS approach. Kotlin Multiplatform with a native or shared UI, a separate Swift app, or a cross-platform framework. Filter firms by whether they have shipped the approach you chose.

Step 3: Match your budget to the minimum. Minimums run from $5,000 to $75,000, and seven firms publish $25 to $49 an hour.

Step 4: Install their apps. Ask for store links to Kotlin apps they built and still maintain, and check the update history.

Step 5: Ask for the version policy. The answer should name the Play target API level, the Kotlin version, and how fast Android security patches and library updates reach the app.

Step 6: Ask who owns the accounts. The Play Console, the app signing key, the Apple developer account and the repository should be in your name from day one.

Step 7: Buy a paid discovery. For an existing app, a short fixed-fee audit of the target API level, Kotlin version, dependencies and crash rate shows the real size of the job.

How to buy Kotlin development: four engagement models

The engagement model decides who pays when the second platform or a store rejection turns out bigger than the estimate.

Fixed price moves overrun risk to the vendor, who prices it in. It suits a new app with settled designs. It fails when store review, device fragmentation or the iOS side are still open questions.

Time and materials keeps the risk with you. It suits migrations and products still finding their shape. Cap each phase and review burn every week.

Support retainer covers the yearly Play target upgrade, Kotlin and library updates, OS releases and a block of change requests.

Staff augmentation adds Kotlin engineers to your team. UplineSoft, X-Team, Jalasoft and Brain Station 23 publish staff augmentation lines. It fails when nobody in-house owns the architecture and release decisions.

The technical question: bringing an Android app up to date

An Android app that has not been touched for a year is usually behind on three things at once: the Play target, the Kotlin version and the UI toolkit. The order decides whether it is a planned project or a rewrite.

Step 1: Meet the Play target first. New apps and updates must target Android 16, API level 36, and existing apps below Android 15 lose availability to new users on newer devices (Android Developers). Until this is done, you cannot ship an update.

Step 2: Move to a supported Kotlin line. Kotlin 2.4 is supported until 3 December 2027 (Kotlin). Anything before Kotlin 2.0 also misses the K2 compiler, which became the default and Stable in 2.0 (Kotlin).

Step 3: Replace kapt with KSP. Google says kapt is in maintenance mode and recommends migrating to KSP, which analyses Kotlin code directly and is up to twice as fast (Android Developers).

Step 4: Convert Java a module at a time. Kotlin is fully interoperable with Java, so there is no need to convert the whole app at once (Android Developers).

Step 5: Build new screens in Compose. Jetpack Compose is Android’s recommended toolkit for native UI (Android Developers). Migrate old XML screens when they next need real changes, not all at once.

Step 6: Share logic before sharing UI. If an iOS app is coming, move networking, data and business rules into a Kotlin Multiplatform module first. Its core is Stable on Android and iOS (Kotlin), and Compose Multiplatform for iOS has been stable since May 2025 (JetBrains).

Step 7: Schedule the next round. Kotlin 2.5 is planned for December 2026 (Kotlin), and the Play target requirement is set each year. Budget both as recurring work.

Red flags: eight answers to walk away from

Each of these answers should end the conversation, or at least change the contract.

“We’ll target the API level later.” Updates below Android 16 cannot be submitted to Google Play (Android Developers).

“We’ll rewrite it in Kotlin first.” Kotlin works alongside Java, so conversion can happen a module at a time.

“Kotlin Multiplatform isn’t ready.” Its core is Stable on Android and iOS (Kotlin). Ask for a reason specific to your app.

“We’ll build iOS separately later.” Ask for the cost of both platforms now, since iOS is the US majority.

“kapt is fine.” Google recommends KSP and describes kapt as in maintenance mode (Android Developers).

“We’ll keep the signing key for you.” The upload key and Play App Signing settings should be under your account.

“We publish under our developer account.” The Play Console and Apple developer accounts must be yours.

“Crash reporting is optional.” Without it, nobody sees the crashes Kotlin was meant to reduce.

After launch: what the build quote leaves out

This part covers what owners wish they had settled before the final invoice, and what recurs for as long as the app is in the stores.

What you must own before the final invoice

The code repository with its full history, in your GitHub or GitLab organisation, not a zip.

The Google Play Console developer account, registered to your organisation, with the vendor added as a user you can remove.

The app signing and upload keys, with Play App Signing enrolled under your account and the upload keystore and its passwords in a vault you control. A key held by the agency leaves with the agency.

The Apple developer account and App Store Connect, if the app ships on iPhone.

Firebase, analytics, crash reporting and push notification projects, owned by your organisation.

Back-end hosting, domain and API keys, with billing in your name.

Design source files, so the next team can extend them.

A runbook, covering builds, release, rollback, the store review process and incident contacts.

The bill that arrives after launch

A build quote covers the build. Ask for the recurring number before you sign, and compare vendors over three years.

The yearly Play target upgrade comes first, because it is not optional. Then Kotlin and library updates, which follow a release about twice a year (Kotlin); back-end hosting; testing on new devices and OS versions; monitoring; and store account fees. Change requests usually outgrow everything else by year two.

Security is a recurring cost

Android itself ships monthly fixes. The September 2026 Android Security Bulletin’s most severe issue was a critical flaw in the System component that could lead to remote code execution with no additional privileges needed (Android Security Bulletin). Your app does not control device patching, but it does control its own dependencies, its target API level and how fast it ships fixes.

Google Cloud’s M-Trends 2026 estimated the mean time to exploit at minus seven days, meaning exploitation often arrives before a patch (Google Cloud). Write a release window, in days, for security fixes into the support agreement, and keep the Play target current so updates can ship at all.

Accessibility is legal exposure

WebAIM found detected WCAG 2 failures on 95.9 percent of the top million home pages in 2026 (WebAIM Million 2026), and more than 5,000 digital accessibility lawsuits were filed in 2025 (UsableNet). Apps are not exempt. Name WCAG 2.2 AA in the contract, test with TalkBack and VoiceOver in the definition of done, and include content descriptions and scalable text in code review.

Contract clauses that surface in month nine

IP assignment on payment, not on final acceptance.

Transition assistance, a fixed number of hours at an agreed rate, available whether the relationship ends well or badly.

Rate escalation caps for the support period.

Subcontracting, named and approved in writing, including any offshore delivery centre.

A release window, in days, for critical security fixes.

A store compliance clause, making the vendor responsible for meeting the current Play target and store policies during the support term.

Non-solicitation in both directions, with a reasonable term.

This is general guidance, not legal advice. Have your own counsel review the contract.

How to leave without losing the codebase

Confirm, in writing, that the repository, store accounts, signing keys and cloud projects are already yours. Trigger the transition hours while the relationship is still cordial. Ask the departing team to record walkthroughs of the build and release process, the architecture and any migration still in progress, and to ship one release in front of your staff.

On the last day, remove the departing team from the Play Console, App Store Connect, Firebase and the repository, and rotate every API key and credential they could have seen.

Hire in-house or hire a Kotlin development company

The comparison starts with the wage. PayScale reports $115,000 for the Kotlin skill and Indeed $139,972 for Android developers (PayScale; Indeed). That is before benefits, recruiting, devices and the time to hire.

Hire in-house when the app is your product and ships every week. Knowing the users and the codebase is the asset.

Hire an agency for a new app, an iOS expansion or a catch-up on the Play target and Kotlin version, with the store accounts in your name and transition hours in the contract.

Mix the two when you have a mobile lead but not enough engineers. Staff augmentation fills the gap, and your lead keeps the architecture and release decisions.

FAQ

Conclusion

The data behind this Top 20 Kotlin Development Companies in USA list says three things. Kotlin is a minority share at most of these firms, with a median of 17.5 percent of their languages, and most also sell Flutter or React Native. Only two of their 199 first-page reviews name Kotlin, so the evidence has to come from apps you can install and code you can read. And prices are moderate, with a median minimum of $25,000 and fourteen firms whose typical project is under $50,000.

Any of the twenty can ship an Android app. What decides the next three years is whether the app keeps up with the Play target and the Kotlin calendar, whether iOS is planned rather than bolted on, and whether the store accounts, signing keys and repository are in your name when the work is done.

Sources

• https://clutch.co/us/developers/kotlin?sort_by=ClutchRank
• https://clutch.co/profile/brain-station-23
• https://developer.android.com/google/play/requirements/target-sdk
• https://kotlinlang.org/docs/releases.html
• https://kotlinlang.org/docs/whatsnew20.html
• https://kotlinlang.org/docs/multiplatform/supported-platforms.html
• https://blog.jetbrains.com/kotlin/2025/05/compose-multiplatform-1-8-0-released-compose-multiplatform-for-ios-is-stable-and-production-ready/
• https://developer.android.com/kotlin/first
• https://developer.android.com/compose
• https://developer.android.com/build/migrate-to-ksp
• https://survey.stackoverflow.co/2025/technology
• https://gs.statcounter.com/os-market-share/mobile/united-states-of-america
• https://www.payscale.com/research/US/Skill=Kotlin_Programming_Language/Salary
• https://www.bls.gov/ooh/computer-and-information-technology/software-developers.htm
• https://www.indeed.com/career/android-developer/salaries
• https://source.android.com/docs/security/bulletin/2026/2026-09-01
• https://cloud.google.com/blog/topics/threat-intelligence/m-trends-2026
• https://webaim.org/projects/million/
• https://blog.usablenet.com/ada-web-lawsuit-trends-2026