Services · Mobile
Mobile app development agency in London
iOS and Android apps from one React Native and Expo codebase, with the API behind them and the App Store and Google Play release, built by a London software studio.
Digital Souls Studios builds mobile apps for iOS and Android from a single codebase in React Native and Expo, together with the API and database behind the app and the marketing site beside it. The work runs from a written specification through design, build and store submission, and the studio supports the app after release.
The studio's own Calorie Genie is the proof: an AI calorie tracker released on the App Store in June 2026 and also on Google Play, available in 45 languages, free to download with a Premium tier. The app, its Express and PostgreSQL API and its Next.js marketing site were all built here.
What we build
- iOS and Android appsOne React Native and Expo codebase that ships to both stores, with native modules where a feature needs them.
- The API behind the appAccounts, data, subscriptions and sync, built as a service the app and a web dashboard can share. See custom software development.
- AI in the appA camera or text feature backed by a language model, as in Calorie Genie's photo, barcode and menu scanning. See AI and automation.
- Subscriptions and in-app purchaseA free tier and a paid tier, with the store billing wired in.
- Store releaseApp Store and Google Play listings, submission and the review process, as part of the launch step.
- The site beside the appA Next.js marketing site for the app, built for search. See web development.
How a mobile build is done
The specification lists the screens, the data, the device features the app needs (camera, notifications, location) and the business model, so the store rules that apply are known before the build starts. Design is for the core flow first.
Builds are tested on real devices during production, and the store review is treated as part of the launch rather than an afterthought. After release the same codebase carries updates to both platforms, and localisation is a configuration step: Calorie Genie ships in 45 languages from one build.
Who does the work
Isaac Surfraz leads engineering, with about a decade across software, AR/VR and platform architecture. Catalina Crisan leads product and designs the interface. Lucas Comte builds the back end. The three are on the studio page.
01-04
How a project moves
From discovery to deployment, we handle design, engineering, infrastructure, and launch.
- 01
Specification
Tell us about the idea in writing. We put together a specification tailored to the work.
- 02
Production
We design and build it, with regular updates rather than a long silence.
- 03
Launch
We help launch the project and leave it in a state a team can run.
- 04
Support
If you would rather not run it alone, support packages cover maintenance after launch.
Recent public dates: Calorie Genie reached the App Store in June 2026 and is also on Google Play. The timeline for a new app is set in the specification.
Technologies
React Native with Expo for the app, Express and PostgreSQL for the API, OpenAI models where the app has an AI feature, and Next.js for the site beside it. The same stack as the studio's web work, so one team covers the app, the service and the site.
Related work
Questions
- How much does it cost to build an app in the UK?
- It depends on the screens, the API behind the app and whether it needs AI or payments, so project work is quoted in writing after the specification. The published UK bands and day rates are in the app cost guide. The published packages on the home page cover ongoing work after release.
- Do you build native apps or cross-platform?
- Cross-platform in React Native and Expo: one codebase for iOS and Android, with native modules where a feature needs them. Calorie Genie is built this way.
- Do you publish the app to the stores?
- Yes. Store listings, submission and review are part of the launch step. Calorie Genie is published by the studio on both stores.
- Can you add AI to a mobile app?
- Yes. Calorie Genie reads a photo of a plate, a barcode or a restaurant menu and returns nutrition using OpenAI models, through an API the studio built.
- Do you work with businesses outside London?
- Yes. The studio is in London and works remotely.