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Common developer tools like JSON formatting and UUID generation, right in your browser.
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- JSON Formatter
Format JSON to make it easy to read.
- UUID Generator
Generate multiple UUIDs (v4) at once.
- JWT Decoder
Decompose a JWT into its header, payload, and signature.
- SQL Formatter
Format SQL into a readable, well-indented layout.
- Base64 Encode / Decode
Encode and decode text to and from Base64.
- Unix Timestamp Converter
Convert between Unix timestamps and dates.
- Regex Tester
Test a regular expression pattern and check the matching results.
- Text Diff
Compare two texts and display the differences line by line.
- Color Converter
Convert color codes between HEX, RGB, and HSL.
- IP Subnet Calculator
Calculate network information from an IPv4 address in CIDR notation.
What's New
You can now choose AES-CBC, AES-GCM, or AES-CTR and encrypt or decrypt with your own key and IV, so you can work with ciphertext from other systems such as Java, PHP, and OpenSSL.
You can now add and remove items and set flex-grow, flex-shrink, flex-basis, order, and align-self for each item. The preview and CSS update as soon as you change a value.
- 2026-09-24Published guides (Japanese only)
Published Japanese-language guides on line endings, character encoding problems, timestamps, age calculation, and color contrast, and added in-depth explanations to 10 major tool pages in Japanese.
- 2026-09-19Added Image Cropper
Added a tool to crop an image freely by dragging on it.
- 2026-09-19Added HTTP Headers Reference
Added a tool to look up commonly used HTTP request and response headers.