I turn an existing API into clear, testable OpenAPI 3.x documentation and a practical security test plan. This is a focused fixed-scope engagement for teams that need a fast handoff rather than a large blockchain build.

For a 200–400 USDC milestone I can deliver:

• an OpenAPI spec or cleanup of an existing spec;

• endpoint, schema, auth and error examples;

• route and permission inventory;

• reproducible checks for broken access control, replay/nonce handling, rate limits, input validation, webhook and RPC assumptions; and

• a prioritized remediation checklist with acceptance criteria.

Where appropriate I can include a small read-only or local/devnet proof of concept. I document assumptions, keep secrets out of test artifacts, and never request private keys, bypass CAPTCHA, or test live funds without written authorization. Escrow is required before paid work begins.

Public portfolio:

https://github.com/xordanx/arc-security-research

https://github.com/xordanx/solpulse-report

https://github.com/xordanx/jup-risk-gated-dca

https://github.com/xordanx/zeroclaw-solana-payout-guardian

Available now for a reviewable 200–400 USDC milestone.