Developer Tools
Handy utilities for developers and programmers
Select a tool below. Every tool runs locally in your browser and is free to use.
๐ป Developer Tools ยท Total 42 tools
AES Encrypt / DecryptEncrypt and decrypt text with AES-256-GCM using WebCrypto in your browser - nothing is uploaded.
Caesar CipherEncrypt and decrypt text with the Caesar cipher - any shift 1-25, letters only, case preserved.
Code128 Barcode GeneratorGenerate Code128 barcodes (Code B) with automatic checksum as SVG - for logistics labels and internal codes.
Cookie FormatterParse Cookie strings to JSON/table with URL decoding, or build Cookie strings from JSON.
CRC32 / Adler-32 ChecksumCompute CRC32 and Adler-32 checksums in hex and decimal for data integrity checks.
Cron Expression ParserParse 5-field cron expressions into readable descriptions and the next N run times, with ranges, steps and lists.
CSS Formatter & MinifierBeautify or minify CSS code with one click - removes comments and extra whitespace.
CSV to Markdown TableConvert CSV data to Markdown table syntax with comma, semicolon or Tab separators.
Download Time CalculatorEstimate download time from file size and connection speed (MB/GB and Mbps).
.env FormatterParse and format .env files with aligned KEY=VALUE, or convert to JSON.
.gitignore GeneratorGenerate .gitignore rules for popular languages and frameworks (Node, Python, Java, Go, Vue...) with custom lines.
Gzip Compress/DecompressCompress text to Base64-encoded Gzip and decompress it back, with compression ratio.
HMAC-SHA256 GeneratorCompute HMAC-SHA256 signatures from a message and secret key - for API signing and integrity checks.
HTML Encode/Decode & HTML to JSHTML escape/decode, deep numeric-entity encoding, and convert HTML to JS string literals.
HTML PrettifierBeautify or minify HTML code with automatic indentation.
HTML Table GeneratorGenerate HTML table code from CSV data with header, border and class options.
HTML to MarkdownConvert HTML to Markdown with headings, links, images, lists, code and quotes.
HTTP Status CodesLook up HTTP status codes 1xx-5xx with meanings and usage - a quick reference for developers.
IP Subnet CalculatorCalculate network address, broadcast, usable host range, subnet mask and host count from an IPv4 and prefix.
IPv6 Expand & CompressExpand compressed IPv6 addresses to full form or compress them back, with validation.
JavaScript Formatter & MinifierBeautify or minify JavaScript code while safely handling strings, templates, comments and regex literals.
JSON FlattenerFlatten nested JSON into dot-path key=value pairs with array indexes and custom separators.
JSON to CSVConvert a JSON array to CSV with custom delimiters, headers and one-click copy.
JSON to TypeScriptGenerate TypeScript interfaces from JSON objects with nested types and arrays.
JSON to YAMLConvert JSON to YAML with nested objects, arrays and proper string quoting for config files.
JSON Tree ViewerRender JSON as a collapsible color-coded tree with expand/collapse-all - perfect for debugging and learning.
JWT Encoder (HS256)Generate HS256-signed JWTs from header, payload and secret - for API testing and learning.
MAC Address GeneratorGenerate random MAC addresses in bulk with custom separators, case and prefixes for network testing.
Markdown Table GeneratorVisually edit rows and columns to generate Markdown table code with headers.
Markdown to HTMLConvert Markdown to HTML with headings, bold, italic, links, lists, tables, code blocks and quotes.
Markdown TOC GeneratorGenerate a linked table of contents from Markdown headings with nested indentation.
MD5 Hash GeneratorCompute MD5 digests (32 hex chars) for UTF-8 text, fully in your browser.
MIME Type LookupLook up MIME types by file extension or Content-Type for common images, documents, audio and video.
Random IP & Port GeneratorGenerate random public IPv4/IPv6 addresses with ports, or validate ip:port pairs - great for test data.
SQL FormatterBeautify SQL statements with keyword uppercasing, line breaks and indentation for readability.
String Escape/Unescape (JS)Escape strings to JavaScript-safe form (quotes, newlines, control chars) and unescape them back.
Unicode Encode/DecodeConvert text to \uXXXX Unicode escapes (with surrogate pairs for emoji) and back.
User-Agent ParserParse a browser User-Agent string to identify browser, version, OS and device type.
UTF-16 Encode/DecodeConvert text to \xXXXX UTF-16 hex escapes and back, useful for deobfuscating scripts.
XML to JSONConvert XML documents to JSON, handling attributes, nested elements and repeated nodes automatically.
YAML FormatterParse and reformat YAML with clean indentation and quoting for readable config files.
YAML to JSON ConverterConvert YAML (indent-nested maps, lists, comments, scalars) to pretty JSON for config files.
FAQ
What is the Developer Tools category?
The Developer Tools category includes 42 free online tools for common needs. All run locally in your browser - no sign-up or install required.
Are these tools free?
Yes, all tools are free with no usage limits.
Do I need to register?
No. Open a page and use it right away - your data stays in your browser.
Which languages are supported?
This site supports 12 languages: Chinese, English, Japanese, Korean, Spanish, French, German, Portuguese, Russian, Arabic, Indonesian and Hindi.