Developer tools
Inspect and debug the formats you work in every day, without pasting production data into someone else's server.
These are the tools you reach for when something is nearly working. A regular expression matches four things instead of three; a JSON response parses in one service and not the next; a token is being rejected and the error says only that it is invalid. In each case the problem is that the data is opaque, and the fix is to see it.
The regex tester, the JSON viewer and the JWT decoder all run as JavaScript in your own browser — you can disconnect from the internet after the page loads and they keep working, which is what makes it reasonable to paste a real token or a real API response into them. The Open Graph checker is the one exception on the whole site: it has to fetch the page you name, because a browser is not allowed to read another origin's HTML, so the address you give it does reach our server. It is the only tool here that does.
4 tools in developer
Test and explain regular expressions with real-time matching and plain English explanations.
Try nowFormat, validate, and beautify JSON data with syntax highlighting and error detection.
Try nowDecode a JSON Web Token, read its claims, check expiry, and verify HS, RS or ES signatures — without the token ever leaving your browser.
Try nowSee how a link will look when shared, and what's stopping the preview image from showing.
Try nowWhich one do you need?
- A pattern isn't matching what you expected
- The regex tester highlights every match live as you type and breaks the pattern down into plain English, which usually finds the problem faster than re-reading the pattern does.
- A JSON payload is too nested to read
- The JSON viewer draws it as an expandable tree with values coloured by type, and reports the parse error in plain language when the JSON is malformed.
- An API is rejecting your token
- The JWT decoder shows the header and claims, says when the token expired in so many words, and verifies HS, RS and ES signatures if you supply the key.
- A shared link shows no preview image
- The Open Graph checker fetches the page and reports which tags are present, which are missing, and what is stopping the image from rendering on each platform.
Guides for these tools
Frequently asked questions
Is it safe to paste a real token or production response here?
For the regex tester, JSON viewer and JWT decoder, yes — they never transmit what you paste, and you can confirm that in your browser's network tab or by going offline after the page loads. The Open Graph checker is different: it sends the URL you enter to our server so it can fetch that page. Don't put anything confidential in a URL you give it.
Do I need an account or an API key?
No. There is nothing to sign up for, no rate limit and no key. Every tool works fully on the first visit.
Which regex flavour does the tester use?
JavaScript's, because it is running in your browser's own engine. Most patterns are portable, but lookbehind support, named groups and Unicode property escapes differ between engines — check against your target language if the pattern is going into PCRE, Python or Go.