Developer Tools Calculators

Free online developer tools calculators and tools, including Base64 Encoder/Decoder, Colour Converter & Contrast Checker, Diff Checker. Fast, simple and easy to use.

15 tools
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Base64 Encoder/Decoder

Encode Unicode text or decode standard and URL-safe Base64 locally.
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Colour Converter & Contrast Checker

Convert HEX to RGB and HSL and check WCAG colour contrast.
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Diff Checker

Compare two text blocks line by line with added and removed lines.
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Hash Generator

Generate SHA-256, SHA-1, or MD5 hashes locally from UTF-8 text.
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HTML Formatter

Indent and inspect HTML markup locally without executing pasted code.
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JSON Formatter

Format, validate, and beautify JSON data with syntax highlighting.
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JWT Decoder

Inspect JWT headers and payloads locally without implying signature verification.
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Markdown Previewer

Preview common Markdown locally with escaped raw HTML and safe links.
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Regex Tester

Test JavaScript regular expressions with matches, groups, limits, and a timeout.
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SQL Formatter

Format and beautify SQL queries for better readability.
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Text Case Converter

Convert text to upper, lower, title, camel, Pascal, snake, and kebab case.
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Unix Timestamp Converter for Developers

Convert Unix seconds or milliseconds to UTC and local date-times.
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URL Encoder/Decoder

Encode or decode URL components and complete URLs locally.
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UUID Generator

Generate secure UUID v4 identifiers individually or in batches.
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XML Formatter

Format and validate XML locally with DTD and entity declarations blocked.