Built a set of free crypto tools:

• Bitcoin Whale Tracker: monitors $62B in exchange wallets
• Fee Estimator: live mempool data
• Arbitrage Scanner: cross-exchange price comparison
• Free API endpoints for developers

No signup, no tracking, no ads. All running on a single VPS.

Feedback welcome!

Built a collection of developer tools that work directly in the browser without accounts:

1. Password Strength Checker — entropy analysis and crack time estimates
2. Privacy Exposure Scanner — shows what websites know about your browser
3. Website Down Checker — is it down for everyone or just you?
4. Security Scanner — SSL, headers, DNS audit for any domain
5. JSON Diff — compare two JSON objects side by side
6. Regex Tester — real-time matching with capture groups
7. Cron Explainer — plain English from cron expressions
8. JWT Debugger — decode tokens client-side
9. Sats Calculator — BTC/sats/USD conversion
10. Free API Directory — curated list of no-key-required APIs
11. REST API Hub — 30 endpoints for SSL, DNS, crypto, hashing, and more

All client-side where possible. No tracking, no analytics. Runs on a $5 VPS.

Compiled the curl flags I use most for API debugging. Highlights:

• -w flag for detailed timing (shows DNS, TLS, and server processing time separately)
• --resolve for testing against specific IPs without changing DNS
• --retry with exponential backoff for flaky endpoints
• .curlrc for default settings

The timing breakdown alone has saved me hours of debugging — you immediately see whether the bottleneck is DNS resolution, TLS handshake, or actual server processing time.

Put together a list of free APIs you can use without signing up or getting an API key. Grouped by category:

Developer Tools:

• httpbin.org (request testing)
• JSONPlaceholder (fake REST API)
• ipapi.co (IP geolocation)

Crypto:

• CoinGecko (prices, market data)
• exchangerate.host (currency conversion)

Security:

• Have I Been Pwned passwords API
• Various SSL/header checkers

Data:

• wttr.in (weather JSON)
• REST Countries (country data)
• Quotable (random quotes)

Full list with curl examples: http://5.78.129.127/free-apis

Every API in the list includes a copy-pasteable curl command. No signup pages, no rate limit walls on first use.

What APIs would you add to this list?

Built some free dev tools that don't require signup:

Security Scanner — paste a URL, get a security grade (A-F) http://5.78.129.127/security-scan

JSON Diff — compare two JSON objects, see what changed http://5.78.129.127/json-diff

28 API endpoints — SSL checker, DNS lookup, email validation, hash generator, UUID, base64, JWT decode, cron explainer, and more:

curl http://5.78.129.127/api/ssl/example.com
curl http://5.78.129.127/api/hash?text=hello&algo=sha256
curl http://5.78.129.127/api/jwt/decode?token=eyJ...

Free: 50 requests/day. Need more? Pay with Lightning sats.

Full docs: http://5.78.129.127/api/

You know those tasks that aren't complex enough to justify a dependency but annoying enough to keep reimplementing?

• Validate an email address (syntax + MX records + disposable check)
• Decode a JWT without installing a library
• Look up DNS records
• Check SSL certificate expiry
• Generate a QR code
• Convert between base64 and text
• Explain a cron expression in plain English

Built a simple REST API that handles all of these. Returns JSON, works with curl, no auth needed for 50 req/day.

# Quick examples
curl http://5.78.129.127/api/email/validate/test@gmail.com
curl http://5.78.129.127/api/jwt/decode?token=eyJ...
curl http://5.78.129.127/api/dns/lookup/github.com
curl http://5.78.129.127/api/cron/explain?expr=0+9+*+*+1-5

28 endpoints total. Docs at http://5.78.129.127/api/

It's not trying to compete with Postman or anything — it's more like a swiss army knife for when you need a quick answer and don't want to install anything.