Description

I'm Leon, a mobile app developer and solo founder from Germany. I ship production Expo / React Native apps and specialize in solving complex technical problems in existing mobile applications.

I typically help with:

• Fixing difficult Expo / React Native production issues

• iOS / Android build & release debugging

• Performance bottlenecks and memory issues

• Offline-first architecture & sync design

• Subscription / RevenueCat integration

• App Store / Play Store rejection fixes

• Complex navigation and state architecture

• Media upload pipelines (video, images, background processing)

• Cloudflare / serverless backend integration

My focus is deep technical problem solving and short, well-defined engagements where experience matters.

Technical background:

• Expo / React Native (production apps on App Store & Google Play)

• TypeScript

• Expo Router & complex navigation

• Offline-first architectures (SQLite, MMKV, sync systems)

• Cloudflare Workers / serverless backends

• GraphQL & REST APIs

• RevenueCat & in-app purchases

• Push notifications

• Media processing pipelines

• Performance optimization

If you have a specific production issue or architectural challenge, I can usually help quickly.

Languages

German
Native or bilingual
English
Fluent

Workplace preferences

Remote only

Primarily works remotely

MaibornWolff GmbH
Miele Cloud Services - IoT Backend Software Engineer
November 2025 - January 2026 (2 months)
Berlin, Germany
Worked on IoT cloud backend (Miele Cloud Services): bug analysis, small features, REST APIs (OpenAPI), dependency updates, and improved testing strategy with integration tests.
Java Spring Boot Java Kubernetes PostgreSQL Apache Kafka
MaibornWolff GmbH
MaibornWolff GPT: Internal GPT Platform and AI Agent
April 2025 - August 2025 (4 months)
Berlin, Germany
Build, deployed internal GPT platform (self hosted ChatGTP clone) in a team with three other engineers to push t copanies transformation to an AI-first approach. We also build a company LLM agent that had access to internal documents and could answer questions to employees based on this data.
Microsoft Azure Retrieval-Augmented Generation (RAG) LLMs AI Agents
ClimbTag
Founder and Developer
March 2025 - Today (1 year and 3 months)
Berlin, Germany
Built a production mobile app used in climbing gyms to log boulder ascents via QR tags. Includes offline logging, gym-scoped sync, video uploads, and a serverless Cloudflare backend. Focus on performance, scalable architecture, and real-world usage.
Software Architektur Expo React Native Cloudflare Local-First

Check out Leon's experience

Be the first to recommend Leon

Help this freelancer shine by sharing your experience working together.

Agatha Frydrych

Backend Java Software Engineer

4.7

(3)

Baptiste Duhen

Fullstack developer

4.6

(4)

Amed Hamou

Senior Lead Developer

(2)

Audrey Champion

Web developer

4.3

(3)

Signup to reveal

Bachelor Computer Science
Technical University Munich
2022
Master Computer Science
Technische Universität Berlin
2026

Leon Jünemann

Expo / React Native Expert, Cloudflare Expert

About Leon

Experience

Recommendations

These freelancer profiles also match your criteria

Education

Skill set

Categories