Developer Tools
JSON, Base64, URL, UUID, hashing, JWT, regex and other coding utilities.
JSON Formatter
Format and pretty-print JSON with validation and clear error messages.
Open tool →Developer ToolsJSON Minifier
Minify valid JSON into a compact one-line form.
Open tool →Developer ToolsJSON Validator
Check JSON syntax and report where parsing fails.
Open tool →Developer ToolsBase64 Encoder / Decoder
Encode plain text to Base64 or decode Base64 back to text.
Open tool →Developer ToolsURL Encoder / Decoder
Encode or decode URL components safely in the browser.
Open tool →Developer ToolsUUID Generator
Generate RFC 4122-style version 4 UUIDs using the browser crypto API.
Open tool →Developer ToolsPassword Generator
Generate strong random passwords with adjustable length and character sets.
Open tool →Developer ToolsSHA-256 Hash Generator
Create a SHA-256 hash from text using the browser Web Crypto API.
Open tool →Developer ToolsUnix Timestamp Converter
Convert between Unix timestamps and local or UTC date-time values.
Open tool →Developer ToolsJWT Decoder
Decode JWT header and payload data locally without sending the token anywhere.
Open tool →Developer ToolsHTML Entity Encoder / Decoder
Encode special HTML characters or decode HTML entities back to text.
Open tool →Developer ToolsRegex Tester
Test a JavaScript regular expression against text and inspect matching results.
Open tool →Why this category exists
Costovia groups related utilities so visitors can move from one task to the next without starting another search. Every tool has a dedicated URL and links back to this hub.
Explore Developer Tools
Format and validate JSON, test regex, decode JWT, work with Base64, URLs, UUIDs, hashes and other developer utilities online.
Inspect and format developer data
Validate JSON before reformatting or minifying it. Formatting changes readability; minification reduces whitespace. Review the tool output before copying it into an application.