Daniel Lehr

Frontend and product engineer focused on developer tools, API infrastructure, and AI systems. I lead Zudoku, Zuplo's open‑source API documentation framework. Over ten years in product engineering, I have mostly built what developers use directly: portals, docs, design systems, and agent tooling.

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

Experience

Zuplo

June 2024 – present · remote

Senior Software Engineer

Zuplo is a programmable API gateway with a built-in developer portal, monetization, and MCP support.

Zudoku

Open sourceLead maintainer · MIT · 580+ stars · github.com/zuplo/zudoku

Zudoku is Zuplo's open-core API documentation framework, written in React and TypeScript on Vite. It is the engine behind the commercial developer portal, and MIT‑licensed so the community can extend it with plugins.

  • Lead Zudoku's development as its primary maintainer and own its architecture and release pipeline
  • Zudoku powers every Zuplo customer portal, including AccuWeather's portal for an API handling billions of calls per month
  • Built Zudoku as a Vite-powered framework, including its plugin architecture, OpenAPI rendering, interactive API playground, theming, auth, and search
  • Built monetization across Zuplo and Zudoku: a plugin that renders pricing and plans in customer portals, plus the gateway plan editor behind AccuWeather's redesigned self-service portal
  • Built customer-facing AI Gateway tooling for provider setup, policies, team access, usage limits, and analytics. Also built MCP endpoint setup for Claude, ChatGPT, Cursor, and VS Code
  • Shipped the API key service redesign, OpenAPI designer, and shared component library, owning the UX and implementation
  • Built the customer developer portal for Rewiring America on Zudoku, with Clerk authentication
  • Built the pipeline in Zuplo's CLI and deployer that turns customer portal configs into deployed Zudoku sites

Stellate

October 2022 – April 2024 · remote

Senior Software Engineer

Stellate was 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 exposed backend logic in the frontend, so users could see query complexity for rate limiting and how the cache would split a query

Tocsen

April 2020 – August 2022 · Freiburg

Senior Software Engineer

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

  • Built the React Native app that pairs with the sensor over BLE, including a custom protocol for over-the-air firmware updates
  • Built the safety backend: 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.

  • Built configurable React/Redux web apps from scratch, including a tenant social network and marketplace
  • Published allthings/elements, an open-source design system that let third parties extend the app

ADITION Technologies

July 2013 – May 2016 · Freiburg

Software Engineer

IT-Systemkaufmann apprenticeship at ADITION · September 2010 – June 2013

Selected AI work

  • Built Zuplo AI with Mastra and the AI SDK, a portal agent running on Cloudflare Workers that helps developers configure, test, and troubleshoot APIs. Mutating tools require approval, and tool calls are traced
  • Built an autonomous Claude routine that reads Slack, Intercom, GitHub, Linear, on-call, and calendar activity and writes a prioritized weekday briefing.

Technical skills

Core web
TypeScriptJavaScriptSemantic HTMLModern CSSReact
Product UI
Design systemsAccessibilityResponsive designReact NativeTailwind CSSshadcn/ui
Developer tools
ViteRolldownPlugin architectureVitestPlaywrightGitCI/CD
AI engineering
MastraAI SDKMCPTool callingAgent workflowsClaude CodeGitHub Copilot
APIs & platform
Node.jsOpenAPIGraphQLRESTAPI design & DXDeveloper portalsEdge & serverless (Cloudflare Workers)SQLWebAssembly