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Offline Developer Tools
Handle common development chores without pasting source data into a remote service. The collection covers JSON, Base64, regular expressions, identifiers, timestamps, colors, and unit conversions.
60 tools
Open a hosted tool or download its standalone version from the main directory.
- JSON FormatterFormat, validate, sort, and minify JSON locally in your browser.
- File HashCalculate SHA-256, SHA-384, or SHA-512 checksums locally.
- Base64 ConverterEncode and decode Unicode text or files as Base64 without uploads.
- Timestamp ConverterConvert local dates, ISO values, and Unix timestamps entirely offline.
- Password GeneratorGenerate strong random passwords locally with the Web Crypto API.
- URL EncoderEncode and decode URL components or complete URLs locally in your browser.
- Markdown PreviewWrite and preview common Markdown formatting locally with a safe HTML export.
- Text DiffCompare two text versions line by line and export a unified diff locally.
- JSON Lines ConverterConvert JSON arrays to JSON Lines and JSONL or NDJSON back to a valid JSON array locally.
- QR Code Generator & ReaderGenerate QR codes from text or read QR codes from local images without network access.
- Word CounterCount words in multilingual text.
- Line CounterCount total, non-empty, and blank lines.
- UTF-8 Byte CounterMeasure the exact UTF-8 byte size of text.
- Reading Time CalculatorEstimate reading and speaking time from word count.
- Keyword Density CheckerMeasure exact keyword use within a passage.
- Character FrequencyRank visible characters by frequency.
- Word FrequencyRank words by case-insensitive frequency.
- Palindrome CheckerCheck text while ignoring case and punctuation.
- Anagram CheckerCompare two values while ignoring spaces and punctuation.
- Regular Expression TesterList every JavaScript regular-expression match.
- Email ExtractorExtract unique email-like addresses from text.
- URL ExtractorExtract unique HTTP and HTTPS URLs from text.
- Phone Number ExtractorExtract likely international phone numbers for review.
- Hashtag ExtractorExtract unique Unicode hashtags.
- Mention ExtractorExtract unique @mentions from text.
- IPv4 Address ExtractorExtract and validate IPv4 addresses.
- Hex Color ExtractorExtract unique three-, four-, six-, and eight-digit hex colors.
- Duplicate Line FinderReport repeated non-empty lines and their counts.
- Longest Line FinderRank the ten longest lines with their original numbers.
- Text StatisticsSummarize lines, words, characters, bytes, and sentence count.
- UUID v4 GeneratorGenerate cryptographically random UUID version 4 values.
- Nano ID GeneratorGenerate compact URL-safe random identifiers.
- Random Hex GeneratorGenerate secure random hexadecimal tokens.
- Random Integer GeneratorGenerate unbiased integers from zero through one million.
- Dice RollerRoll one or more fair six-sided dice.
- Coin FlipperFlip a virtual fair coin repeatedly.
- Lorem Ipsum GeneratorGenerate temporary Latin-style layout copy.
- Sample Name GeneratorGenerate clearly fictional names for mockups and tests.
- Sample Email GeneratorGenerate reserved example-domain email addresses.
- Color Palette GeneratorGenerate random hex colors for quick visual exploration.
- Random Date GeneratorGenerate ISO dates between 2000 and 2030.
- Sample CSV GeneratorGenerate harmless sample rows for spreadsheet testing.
- Sample JSON GeneratorGenerate a valid JSON array for parser and UI tests.
- Number Sequence GeneratorGenerate a one-based integer sequence.
- Placeholder Slug GeneratorGenerate predictable placeholder slugs for prototypes.
- Binary / Decimal ConverterConvert binary integers to decimal.
- Hex / Decimal ConverterConvert hexadecimal integers to decimal.
- Octal / Decimal ConverterConvert octal integers to decimal.
- Decimal Base ConverterConvert a decimal integer to any base from 2 through 36.
- Roman Numeral ConverterConvert decimal integers from 1 through 3999 to Roman numerals.
- Byte Unit ConverterConvert bytes to binary and decimal storage units.
- Length ConverterConvert meters to common metric and imperial lengths.
- Mass ConverterConvert kilograms to metric and imperial weights.
- Temperature ConverterConvert Celsius to Fahrenheit and Kelvin.
- Area ConverterConvert square meters to common area units.
- Volume ConverterConvert liters to common liquid-volume units.
- Speed ConverterConvert kilometers per hour to other speed units.
- Duration ConverterBreak a duration in seconds into larger units.
- Angle ConverterConvert degrees to radians, turns, and gradians.
- HEX to RGB ConverterConvert a three-, six-, or eight-digit hex color to RGB values.