Daniel Lehr

I'm a software engineer with over ten years in web and mobile development. With a focus on frontend and UX, I develop across the stack. That includes user interfaces, design systems, and developer tools. At Zuplo, I owned Zudoku, the framework behind all automatically generated customer developer portals, and built tools for API management.

Freiburg, Germanydaniellehr.de/githubdaniellehr.de/linkedinmail@daniellehr.de

Experience

Zuplo

June 2024 – September 2026 · remote

Software Engineer

Zuplo is a platform for managing and monetizing APIs, with automatically generated documentation and tools for AI integration.

  • Owned Zudoku's entire product development, from designing the user experience through implementation and release.

Zudoku

· 590+ stars · github.com/zuplo/zudoku

Zudoku is a Vite-based framework that automatically generates documentation and developer portals for all Zuplo customers. Its MIT‑licensed core can be extended through plugins.

  • Built AccuWeather's developer portal on Zudoku for an API handling more than a billion calls per month.
  • Built a pipeline that automatically provisions a documentation website for every customer account and publishes configuration changes immediately.
  • Developed the interactive API playground, theming, search, OpenAPI rendering, and authentication.
  • Built server-side rendering and static site generation for Zudoku from the ground up on top of React Router.
  • Built another developer portal for Rewiring America on Zudoku with Clerk authentication.
  • Designed and implemented the OpenAPI designer, API key management redesign, and shared component library in the Zuplo Portal.
  • Implemented API monetization: a plugin for pricing and plan displays in Zudoku customer portals and a plan editor in the Zuplo Portal with Stripe integration and usage tracking.
  • Developed AI Gateway interfaces for provider setup, policies, team access, usage limits, and analytics.

Stellate

October 2022 – April 2024 · remote

Software Engineer

Stellate is a GraphQL edge caching and API management platform.

  • Created GraphDoc, an open-source GraphQL documentation generator later acquired by Stellate.
  • Implemented a developer portal generator for GraphQL APIs: landing page, authentication, and docs.
  • Built a reusable design system together with a designer, with automated Figma sync.
  • Created Rust/WASM bridges that made query complexity for rate limiting and cache usage visible in the frontend.

Tocsen

April 2020 – August 2022 · Freiburg

Software Engineer

Tocsen builds a crash sensor for cyclists that detects head impacts and alerts emergency contacts.

  • Built the React Native app that pairs with the sensor over BLE, including a custom protocol for over-the-air firmware updates.
  • Developed native bridges for the BLE module on iOS and Android in Swift and Java/Kotlin, respectively.
  • Built the iOS and Android build and beta release pipeline using Fastlane and GitHub Actions.
  • Built the backend for emergency detection: GraphQL services running on Cloudflare Workers, federated behind an API gateway.
  • Created a cross-platform design system shared between the web and native apps.

Allthings

June 2016 – November 2019 · Freiburg

Senior Software Engineer

Allthings makes a tenant platform for the real estate industry.

  • Developed configurable React and Redux web apps for a tenant social network.
  • Owned the migration of the entire platform from Angular to React.
  • Published the allthings/elements design system with reusable UI components that let internal teams and external developers extend and customize multiple products.

ADITION Technologies

July 2013 – May 2016 · Freiburg

Software Engineer

  • Developed JavaScript for browser-side ad delivery with workarounds for browser differences in HTML, CSS, and JavaScript, including IE6.

IT-Systemkaufmann apprenticeship

September 2010 – June 2013

Vocational training in IT systems and business

Selected AI work

  • Co-developed Zuplo AI from scratch. Users can operate the entire Zuplo Portal through AI, including configuring and testing APIs and troubleshooting. Built with Mastra and the AI SDK on Cloudflare Workers.
  • Created several Claude workflows, including an automated, prioritized briefing before work each weekday. It summarizes activity from Slack, Intercom, GitHub, and Linear and lists calendar events and on-call shifts.

Technical skills

Frontend
ReactTypeScriptJavaScriptHTMLModern CSSTanStack QueryReact RouterAstroReact Native
Product & UI
UX designDesign systemsAccessibilityResponsive designTailwind CSSshadcn/uiStorybookMotion
Developer tools
ViteRolldownpnpmNxoxlint / oxfmtVitestPlaywrightGitHub ActionsCI/CD
AI engineering
Claude CodeCodexAgent workflowsMastraAI SDKMCP
APIs & platform
Node.jsHonoOpenAPIZodGraphQLRESTEdge & serverless (Cloudflare Workers, Vercel)DockerSQLDrizzleWebAssembly