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Free developer tools — formatters, webhook testing, and more.
a2zutil.dev is a fast, growing library of free developer tools — formatters, converters, encoders and live testing utilities — starting with JSON, SQL, string/ID tools and a webhook receiver, with new additions shipping regularly.
The toolkit
Pick a tool and get straight to work.
JSON Formatter
Prettify, minify, validate, stringify and unescape JSON.
OpenSQL Formatter
Indent messy queries with uppercase or lowercase keywords.
OpenString & ID Formatter
Case conversion, Base64, URL encoding and UUID v4 generation.
OpenText Transform
Lines to a delimited list and back, with trim, dedupe and sort.
OpenJSON ↔ CSV Converter
Convert a JSON array of objects to CSV, or a CSV file back to JSON.
OpenJSON Compare
Diff two JSON documents and see every added, removed and changed value.
OpenBIN Checker
Look up a card's issuer, network and country from its BIN/IIN.
OpenTemporary Email
Get a disposable address and watch incoming mail arrive live.
OpenWebhook Receiver
Get a temporary URL and inspect incoming requests live.
OpenJWT Decoder
Coming soon.
Dev Form Builder
Coming soon.
WebSocket Tester
Coming soon.
Why a2zutil.dev
No sign-in required
Open a tool and use it. No account, no email, no paywall prompt.
100% free
Every tool is free to use with no premium tiers.
Instant and private
Most tools run locally in your browser — that data never leaves the page. The webhook receiver, temporary email and BIN checker are the exceptions, since each needs a network round trip to do its job.
Works on any device
Responsive layouts for quick checks on phone, tablet or desktop.
Live testing tools
Get a temporary webhook URL or email address and watch real deliveries arrive live, no signup required.
Latest from us and around the internet
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The difference between a two-minute payload review and a twenty-minute one usually comes down to a few small habits.
SQL Formatting Conventions That Make Code Review Easier
A query that's easy to review is one where the diff shows the actual change, not a reflow of every line around it.
A growing library of free developer tools
Most developer utilities live on scattered single-purpose sites, or in desktop apps that want an account before they will pretty-print a payload. a2zutil.dev takes the opposite approach: one fast, clean interface for the utilities developers reach for constantly — JSON formatting, SQL formatting, string and ID conversion, webhook testing, and steadily more beyond that. The catalog is built to keep expanding, from everyday text and encoding utilities to API and data-format tools, without ever asking for a signup or slowing the page down.
Every formatter runs as pure client-side JavaScript. When you paste a JSON response from a staging API, a query pulled from a slow-query log, or a string you need re-cased or encoded, that text is processed entirely in your own browser and never uploaded. That matters whenever the payload you are debugging contains customer data, internal identifiers, or anything else you would not paste into a random website.
The webhook receiver is the one networked tool in the toolkit: it hands you a temporary URL you can drop straight into any provider's webhook configuration — Stripe, GitHub, Shopify, your own service — and shows each delivery live, headers and body included. It is built for test events during integration and debugging work, and sessions expire automatically so nothing lingers.
Everything on a2zutil.dev is free, anonymous, and built to outlast today's tool list. New formatters, converters and testing utilities get added regularly, so bookmark the tool you use most — or start from the homepage, which stays the fastest way to find whatever gets added next.