Lexem is the version control and testing platform for AI prompts. Commit, diff, branch, rollback, run evals, and deploy LLM prompts safely with eval-gated promotions, regression detection, and a TypeScript/Python SDK.

AppSignal — Get full visibility into app health, errors, and performance

Get full visibility into app health, errors, and performance

Built Lexem because prompt engineering deserved the same discipline we already expect from code. Lexem gives AI prompts: * Version control with commits, diffs, branching, merges, and one-click rollback * Eval + regression testing with exact match, regex, and LLM-as-judge scoring * AI-generated test cases for happy paths, edge cases, and refusals * AI diff analysis that explains prompt changes and potential risks in plain English * Eval-gated deploys across dev, staging, and prod * Token analytics per version and across prompts * SDKs for TypeScript + Python to ship prompt updates without app redeploys * Fully open-source + self-hostable on your own Postgres The goal was simple: make prompt iteration safer, testable, and production-ready.

AppSignal — Get full visibility into app health, errors, and performance

Get full visibility into app health, errors, and performance

Lexem | Version, Eval & Deploy Prompts

Git for prompts. Version, test & deploy AI safely.

Git for prompts. Version, test & deploy AI safely.