Free developer, API & SEO tools

Free online JSON formatter and validator. Beautify, minify and validate JSON instantly in your browser, with clear error messages. No data is uploaded.

Convert a JSON array of objects to CSV in one click. Handles nested values and quoting correctly. Free, private and runs in your browser.

Convert CSV to a JSON array of objects instantly. Supports quoted fields, custom delimiters and automatic number detection. 100% in your browser.

Decode a JWT and read its header, payload and expiry instantly. Runs locally in your browser, your tokens are never uploaded.

Convert a cURL command to fetch, axios, PHP or Python requests code. Free online cURL converter that runs in your browser.

Send GET, POST, PUT, PATCH and DELETE requests to any public API and inspect status, headers, timing and body. Free online REST API tester, no install.

Generate realistic fake JSON data (users, products, orders) for testing APIs and UIs. Choose the number of records and copy as JSON or CSV.

Test regular expressions against sample text with live match results, capture groups and flags. Free online regex tester.

Build and understand cron expressions. Pick minute, hour, day, month and weekday and get a human-readable description and next run times.

Convert Unix epoch timestamps to human-readable dates and back. Supports seconds and milliseconds, UTC and local time.

Encode text to Base64 or decode Base64 back to text with full UTF-8 support. Runs in your browser.

Encode or decode URLs and query strings with percent-encoding. Free, instant and private.

Generate SHA-1, SHA-256, SHA-384 and SHA-512 hashes of any text using the browser's native crypto. Private and instant.

Generate strong random passwords with a cryptographically secure generator. Choose length and character sets. Nothing is stored or sent.

Generate random UUID v4 identifiers in bulk, with uppercase and no-dash options. Uses secure browser randomness.

Check the HTTP response headers of any website, see status, server, caching and security headers (HSTS, CSP, X-Frame-Options) with a quick score.

Check any domain's SSL/TLS certificate: expiry date, issuer, alternative names, protocol and trust status. Get alerted before it expires.

Look up DNS records for any domain: A, AAAA, MX, NS, TXT, CNAME, SOA and CAA. Free DNS record checker.

Trace every redirect hop (301, 302, 307, 308) from a URL to its final destination. Find redirect chains that hurt SEO.

Check if a website is down for everyone or just you. See HTTP status and response time instantly. Free uptime checker.

Check whether common TCP ports (80, 443, 22, 3306…) are open on a public server or domain.

See your public IP address, resolve any domain to its IPv4 and IPv6 addresses and view reverse DNS.

Analyze any page for on-page SEO: title and meta length, H1, canonical, image alt text, Open Graph, structured data, speed and more, with a score.

Generate title, description, canonical, Open Graph and Twitter Card meta tags for any page. Copy and paste into your HTML head.

Generate a robots.txt file with allow/disallow rules and a sitemap line. Control what search engines crawl.

Count words, characters, sentences and paragraphs, estimate reading time and see top keyword density for your content.

Turn any title into a clean, SEO-friendly URL slug. Removes accents, symbols and stop words if you choose.

Generate lorem ipsum placeholder paragraphs, sentences or words for your designs and templates.

Create QR codes for URLs, text, Wi-Fi and more. Download as PNG. Generated in your browser, no sign-up.