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Developer

JSON Formatter

Turn compact or difficult-to-read JSON into clean, indented JSON you can inspect and copy.

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Developer

JSON Validator

Check whether JSON is valid and get a readable error message when the structure is not.

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Security

JWT Decoder

Inspect the header and payload of a JSON Web Token locally without verifying its signature.

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Developer

Regex Tester

Test a regular expression against sample text and inspect every match clearly.

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Time

Timestamp Converter

Convert Unix timestamps and readable dates to compare logs, API values, and event times.

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Security

Password Generator

Create strong random passwords with the length and character groups you choose.

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Text

Word and Character Counter

Count words, characters, lines, sentences, and reading time while you edit.

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Math

Percentage Calculator

Work out percentages, percentage change, and the original value from a percentage.

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Fix a developer problemJSON, regex, URLs, SQL, headers, and network helpersSee developer tools Handle data carefullyEncode, decode, hash, validate, and compare locallySee security tools Calculate a decisionTime, money, percentage, unit, and planning calculatorsSee calculators Understand the whyClear guides for debugging, content, AI, and modern workRead the archive

Fresh reading

New guides with a practical next step.

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A JSON Validation Workflow That Catches API Problems Before DeploymentUse a repeatable JSON validation workflow to catch malformed payloads, wrong types, missing fields, and unsafe assumptions before an API change reache How to Decode a JWT Safely When Debugging AuthenticationLearn what a JWT decoder can reveal during debugging, what it cannot prove, and how to investigate expired or mis-scoped authentication tokens safely.How to Design a Tool Page That Users Finish and Return ToImprove browser utility pages with clear inputs, useful errors, copy actions, privacy cues, and a result flow that supports repeat use.How to Write Search-Friendly Tool Documentation Without Thin ContentBuild useful tool pages that match search intent with clear examples, limitations, privacy notes, and honest next steps.Unix Timestamps: How to Tell Seconds From MillisecondsLearn how Unix timestamps work, how to detect the wrong unit, and how to convert dates safely across APIs, logs, databases, and JavaScript.Regex Flags Explained: Global, Case-Insensitive, and Multiline ModesUnderstand the regex flags that change matching behavior and learn a safe way to test patterns before using them in code or data migrations.Percentage Change vs Percentage Points: The Difference That Prevents Bad ReportsLearn when to use percentage change, percentage points, and percent of total so dashboards and business reports say exactly what the numbers mean.JSON Formatter, Validator, or Minifier: Which Tool Should You Use?Choose between formatting, validating, and minifying JSON based on the problem you are solving and the risk of hiding useful structure.