Developer Tools

Encode, decode, format and validate code and data. Free developer utilities that run entirely in the browser.

All tools are free to use. File size and processing limits may vary by tool.

JSON Formatter

Format compact or single-line JSON with readable indentation. Tidy an API response in your browser and receive a warning when JSON syntax is invalid.

How to format? Paste an API response or config file and format it; copy it into your project. See the JSON Validator for validity checks too.

JSON Validator

Paste suspicious data and run it; valid syntax earns a confirmation, broken syntax an error warning. Checking happens in this browser, data never reaches a server.

How to validate? Paste the JSON into the box and validate. Valid input returns a confirmation; fix and retry when it fails. Use it on API responses and confi

Base64 Encoder

Convert text into UTF-8 Base64 and copy the encoded result. Processing stays in your browser; Base64 is encoding, not encryption or password protection.

How to encode? Paste the text to encode and run it, then copy the result. Handy for data URIs or carrying binary content in API bodies. Use the Base64 Deco

Base64 Decoder

Decode Base64 or a data URL in your browser. View text, preview recognized images and download the decoded file without uploading the input.

How to decode? Paste Base64 or a data URL, or select a TXT/B64 file containing the code. Decode to view text, preview a recognized image or download the fi

UUID Generator

Generate a standard UUID v4 identifier. Every button press creates a new unique value. It uses the browser cryptographic number generator and sends no request to a server.

How to generate? Press the button and copy the value; use it for database keys, file names and request traces. Collision odds are negligible, yet verify prim

Unix Timestamp Converter

Convert a timestamp into a readable date and a date back into a timestamp. Second and millisecond values are supported. Everything runs in this browser, dates are never stored.

How to convert? Paste a value, pick a direction; the result shows in your local timezone and ISO format. Watch midnight boundaries in daily logs.

Regular expression tester

Regular expression tester. Test JavaScript regular expressions locally.

How to use Test JavaScript regular expressions locally. Maximum 100,000 input characters and 1,000 matches; long matches and capture groups are truncat

JWT header and payload decoder

Decode a JWT header and payload; read-only, the signature, issuer and permissions are NOT verified. No secret key needed. Runs in this browser, the token never reaches a server.

How to use Paste the token and decode it; read the expiry and scope fields. A valid signature needs separate verification; this tool only reveals the c

URL component encoder and decoder

URL component encoder and decoder. Encode or decode a URL component as UTF-8.

How to use Encode or decode a URL component as UTF-8. This encodes reserved characters too; use it for individual parameter values. A plus sign is not

Explain a cron expression in words. Each of the five fields is described and the next five run times are listed. Only the five-field form is accepted; a six-field expression with seconds returns an error.

How to read cron? Type the expression and run; fields are explained and the approximate run times appear in your device timezone. Useful to verify field order

JWT Builder

Create HS256/384/512 JWTs from header and payload. Secrets stay on-device.

How to build? Enter header and payload JSON, type a secret and pick HS256/384/512. Signing happens on your device; the secret is never sent. For testing o

TOTP Authenticator

Generate 30-second one-time codes from a secret. Keys stay on-device.

How to generate? Enter the Base32 secret to see the current 6-digit code with countdown. Never share real account secrets.

API Token Generator

Generate random API keys and secret tokens. Choose 8 to 256 bytes, pick hex, Base64, Base64URL or alphanumeric, and add an optional prefix. The browser cryptographic number generator does the work, no network request leaves the page.

How to generate? Set the length and format, generate, then copy the value to the clipboard. A short prefix such as sk helps you recognise a key but adds no s

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