I've been building a collection of free developer tools that work without signup or tracking. All available as both web UIs and API endpoints:

New tools:

• Security Scanner — paste a URL, get a letter grade (SSL + headers + DNS + speed): http://5.78.129.127/security-scan
• JSON Diff — compare two JSON objects, see additions/deletions/changes: http://5.78.129.127/json-diff
• Sats Calculator — USD to Bitcoin satoshis converter: http://5.78.129.127/sats

API examples:

curl http://5.78.129.127/api/ssl/example.com
curl http://5.78.129.127/api/dns/lookup/example.com
curl http://5.78.129.127/api/crypto/sats?usd=10
curl http://5.78.129.127/api/hash?text=hello&algo=sha256

28 endpoints total. 50 free requests/day. If you need more, paid tiers accept Lightning sats.

Full docs: http://5.78.129.127/api/