Residual Labs

Residual Labs is an engineering lab based near Paris, France, working in French and English for small and mid-sized companies. Our IT work centres on three things. Custom software: web applications and SaaS products built with React, Next.js, Node.js and Python, scoped in writing before a line is written. AI systems: assistants, agents and automation wired into the tools a business already uses, rather than another dashboard nobody opens. Developer tooling: CLI, SDK, API and Model Context Protocol servers, the plumbing that makes the rest maintainable. We also run our own products in public. SPARDA adds deterministic verification to code written by AI and is published on npm as sparda-mcp. Residual Audit turns a web address into a technical and visibility report a non-technical owner can act on. Residual Reach structures outbound campaigns while the contact database stays with the client. What we refuse to do is stop at the demo. Most software impresses in a meeting and comes apart in production. We build for the second year: systems that carry load, document themselves, and can be handed to another developer without us in the room. Sources, documentation and credentials belong to the client at the end of every engagement. Our research is published and citable: four deposits on Zenodo (CERN / OpenAIRE), each with its own DOI, covering AI alignment and computational complexity among others. ORCID 0009-0005-7604-4709. And pricing is public, from a catalogue of 89 referenced deliverables.