FlagLint: Open-Source CLI Tool Tackles LaunchDarkly Feature Flag Debt in TypeScript

Feature flag technical debt silently accumulates in TypeScript codebases when rolled-out flags remain embedded in production code, locking in SDK dependencies indefinitely. Most teams rely on grep searches, which cannot distinguish between static flag keys, dynamic wrapper functions, and bulk evaluation calls — each requiring a different migration approach. FlagLint is a free, open-source command-line tool that uses an AST scanner to parse TypeScript source files, classify every LaunchDarkly SDK call site by type and risk level, and generate a migration plan toward the OpenFeature standard. The tool requires no LaunchDarkly API key and can automatically rewrite low-risk static flag calls while flagging high-risk dynamic patterns for manual review. In a sample enterprise checkout service with five source files, FlagLint identified 19 flag usages across 11 unique flags in under 100 milliseconds.