Developer Guides
Copy-paste tutorials for common API problems — CORS fixes, validation, PDFs, geolocation, and more.
Fix CORS Errors in JavaScript: the 5-Minute Proxy Solution
Browsers block cross-origin fetches that lack an Access-Control-Allow-Origin header. Fix it in five minutes by routing the request through a CORS proxy.
2026-06-09
Validate Email Addresses in One API Call (Free Tier)
Validate email syntax, MX records, disposable domains, role accounts, and typo suggestions with a single GET request. Free tier: 1,000 checks per month.
2026-06-09
Merge PDFs Programmatically with a Simple REST API
Combine PDF files with one REST call. Send URLs or base64 inputs, get the merged document back as base64. No native libraries, free tier included.
2026-06-09
Free Currency Exchange Rate API with Live ECB Rates
Convert currencies with European Central Bank reference rates, refreshed each business day. 30+ currencies, free tier of 1,000 requests per month.
2026-06-09
Free IP Geolocation API: Country, City, Timezone in One Call
Resolve any IPv4 or IPv6 address to country, city, coordinates, and timezone with one GET request. GeoLite2-backed with no per-call data fees.
2026-06-09
Convert Coordinates to Plus Codes (Open Location Code) via API
Encode latitude and longitude into Plus Codes (Open Location Code) and decode them back via REST. Geohash, distance, and coordinate conversion included.
2026-06-09
Redact PII from Text Before It Hits Your Logs or an LLM
Detect and redact emails, phone numbers, SSNs, credit cards, and IPs in one request. Returns masked text plus counts by type; detect-only mode included.
2026-06-09
Generate QR Codes via API: PNG, SVG, or Data URI
Generate QR codes server-side with one GET request. PNG bytes, scalable SVG, or an embeddable data URI, with size, margin, and color options.
2026-06-09