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Developer tools that never see your data.

Developer tools that open instantly: format JSON, decode JWTs, test regex, hash strings, convert timestamps. 22 tools, each with its own reference lab, running in your browser. Not sure what you have? Paste it into the identifier.

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JWTJSONUUID v7SHA-256timestampURLcroncolour

keyJSON Web TokenJWT Decoder →

header{"alg":"HS256","typ":"JWT"}

payload{ "sub": "42", "name": "Ada", "exp": 1760000000}

signature43 Base64url chars (32 bytes), not verified here

exp2025-10-09T08:53:20.000Z · EXPIRED 368 days ago

~/most-usedstart here

data_object#1

JSON FormatterFormat, validate, and see where parsers disagree.

key#2

JWT DecoderDecode and verify tokens without sending them anywhere.

regular_expression#3

Regex TesterLive matches, ReDoS timing and flavour differences.

schedule#4

Timestamp ConverterUnix, ISO 8601 and time-zone traps.

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Data & formats

parse, convert, compare

data_objectJSON FormatterFormat, validate, and see where parsers disagree table_chartJSON to CSVFlatten JSON into a table, round-trip tested differenceDiff CheckerMyers and patience diffs, unified patch output markdownMarkdown EditorCommonMark preview with the delimiter rules shown

Encoding & security

tokens, hashes, IDs

keyJWT DecoderDecode, sign and verify tokens with Web Crypto data_arrayBase64Six Base64 variants and strict decoding linkURL EncoderPercent-encoding with 8 encoders compared tagHash GeneratorSHA family with padding explorer and test vectors fingerprintUUID Generatorv4, v5 and v7, plus an inspector for any UUID passwordPassword GeneratorUnbiased random passwords and strength maths

Patterns & numbers

regex, bases, schedules

regular_expressionRegex TesterLive matches, ReDoS timing, 6 flavours compared pinNumber Base ConverterBases 2-36, endianness and integer limits more_timeCron GeneratorExpressions, time zones and dialect translation scheduleTimestamp ConverterUnix, ISO 8601 and 12 epochs side by side

Web & network

DNS, meta tags, icons

dnsDNS LookupDNS over HTTPS, with the wire format decoded travel_exploreMeta Tag GeneratorPixel-accurate title and description truncation starFavicon GeneratorA full icon set and the ICO bytes explained qr_code_2QR Code GeneratorBit stream and Reed: Solomon shown step by step

Colour & text

contrast, palettes, Unicode

contrastContrast CheckerWCAG 2 and APCA side by side paletteColor PaletteOKLCH scales, gamut and colour-blind checks cleaning_servicesText CleanerInvisible characters and Unicode normalisation text_fieldsText Case ConverterLocale-aware case mapping and identifier styles

Other tool categories

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text_fieldsText tools4 tools

Count words three ways, convert case per locale, and strip invisible characters from pasted text.

Word CounterText Case ConverterText Cleaner

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calculateCalculators11 tools

Dates, loans, VAT, percentages, units, paces and compound interest, with the exact arithmetic shown.

Date CalculatorLoan CalculatorUnit Converter

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lanNetwork1 tools

Look up DNS records over HTTPS and see the query and answer decoded byte by byte.

DNS Lookup

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imageImage tools9 tools

Resize, crop, compress, watermark, redact or remove the background, all in the browser.

Image ResizerBackground RemoverImage Crop

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casinoRandom2 tools

Unbiased random numbers and passwords from the Web Crypto generator, with the statistics checked.

Random NumberPassword Generator

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travel_exploreSEO & sharing3 tools

Meta tags with pixel-accurate truncation, favicons and QR codes for links.

Meta Tag GeneratorFavicon GeneratorQR Code Generator

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