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Free Online Developer Tools — JSON, Regex, JWT & More (/developer-tools) runs in your browser when supported—inputs are not uploaded to EverydayTools servers.
Format JSON, test regex, decode JWTs, generate UUIDs, and run daily dev tasks in your browser. Tokens and payloads never leave your device.
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Browser-based developer tools format, validate, decode, and generate dev data—JSON, regex, JWT, UUID, timestamps, Base64—instantly without installing software or uploading payloads to a server.
Developer tools solve small, repetitive tasks during debugging, code review, and API work: prettify a minified JSON response, test a regex before shipping it, decode a JWT to check expiry, or generate UUIDs for seed data.
EverydayTools runs these utilities in your browser with JavaScript. Tokens, API keys, and payloads are processed locally—they are not uploaded to EverydayTools servers. Copy results straight into your IDE, PR, or incident notes.
This hub groups JSON, regex, JWT, encoding, URL, cron, and hash tools so you can pick the right utility in one place.
Validate JSON first, then format; decode JWTs for inspection only (signature not verified); prefer local tools for production tokens.
Concise answers for common searches — definitions, steps, and comparisons.
Free Online Developer Tools — JSON, Regex, JWT & More (/developer-tools) runs in your browser when supported—inputs are not uploaded to EverydayTools servers.
Seconds (10 digits) or milliseconds (13 digits) since 1970-01-01 UTC. Use the Timestamp Converter—confirm which length your API uses.
Validate first when the source might be invalid. Then format for readability.
Caret (^) allows updates that do not change the leftmost non-zero semver digit. Use the Semantic Version Calculator to test ranges.
Choose JSON, regex, JWT, UUID, timestamp, Base64, URL, cron, or hash from the grid.
Drop payloads, tokens, patterns, or text into the tool—no account required.
Check formatted JSON, validation errors, decoded claims, or generated values.
Paste into your IDE, PR comment, config, or runbook.
Common real-world scenarios where this tool saves time.
Format JSON, validate payloads, and inspect tokens when endpoints fail.
Decode JWTs and convert timestamps quickly under pressure.
Beautify JSON, SQL, or CSS for readable PRs and docs.
UUIDs, API keys, hashes, and cron expressions for fixtures.
Step-by-step chains that connect related tools for common tasks.
Input
{"ok":true,"user":{"id":123}}Output
Indented JSON with syntax highlightingSpot structure and syntax issues faster than reading one long line.
Input
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9....Output
Header + payload with exp/iat as readable datesDebug auth without a script—verify signature in your backend separately.
Input
Pattern + test stringOutput
Live match highlighting and capture groupsIterate on patterns before adding them to production code.
Tools apply deterministic transforms (format, encode, decode), validation (JSON syntax), and CSPRNG generation where applicable. JWT decode is inspection-only.
Match your task to the tool on this hub.
| Tool | Best for | Use when… |
|---|---|---|
| JSON Formatter | Readable JSON | Minified API or log output |
| JSON Validator | Syntax check | Find exact error line before format |
| JSON Diff | Two-object compare | Dev vs staging API responses |
| JWT Decoder | Claims inspection | Check exp, roles—no sig verify |
| Regex Tester | Live JS regex | Email, URL, log extraction patterns |
| Timestamp Converter | Unix ↔ date | JWT exp, logs, created_at fields |
| UUID Generator | RFC 4122 IDs | DB keys, test fixtures |
| Base64 Encoder | Text ↔ binary | Headers, embedded payloads |
| Task | Best choice | Why |
|---|---|---|
| Paste JWT from header mid-review | JWT Decoder (local) | No console; works on any machine |
| Format JSON in PR comment | JSON Formatter | Paste-and-go highlighting |
| Debug live page JS/DOM | Browser DevTools | Needs running app context |
| Project-wide Prettier format | VS Code + Prettier | Repo config and git integration |
Third-party upload tools process files on remote servers. Use browser-local tools on this hub for inspection—tokens and payloads stay in memory on your device. Still treat production secrets carefully; local does not mean zero risk on shared machines.
JWT Decoder shows header and payload only—it does not verify the signature. An attacker can forge a payload. Your backend must validate with the correct secret or public key and algorithm before trusting claims.
Run JSON Validator first when the source might be broken (Slack paste, JS object literals, truncated API errors). Formatting invalid JSON hides the error line. Fix syntax, then use JSON Formatter for readability.
JWTs and many URL-safe strings use Base64URL (+/ → -_, optional padding stripped). Decoding with the wrong alphabet corrupts the payload. Pick Base64URL mode or use the JWT Decoder for tokens.
APIs store seconds (10 digits, e.g. 1746172800) or milliseconds (13 digits). Feeding seconds into a millisecond field shows a date in 1970. Check digit count before Timestamp Converter—JWT exp is usually seconds.
Regex Tester uses JavaScript’s engine—the same as Node and Chrome. Test empty strings, Unicode, newlines, and multiple matches with the g flag before shipping. PCRE or RE2 in other languages behave differently.
50% markup on cost is not 50% margin. Margin = (price − cost) ÷ price; markup = (price − cost) ÷ cost. Use Profit Margin Calculator when setting prices, not mental math from markup alone.
Whitespace and key order make raw diffs noisy. Format each payload with JSON Formatter (after validation), then use JSON Diff. Otherwise you chase spacing changes instead of real data changes.
That encodes slashes and colons and breaks the URL. Encode individual query values only; use encodeURI for a full URL when appropriate. Double-encoding (%2520) happens when you encode already-encoded strings.
Hash Generator supports legacy algorithms, but new designs should use SHA-256 or SHA-512 for integrity. MD5/SHA-1 remain acceptable only for non-security compatibility (old cache keys, legacy APIs).
Browser-generated keys are fine for dev fixtures and quick tests (crypto.getRandomValues). Production secrets should be issued by your server’s CSPRNG and rotation policy—not copied from a one-off generator tab.
Likely cause: Trailing commas, single quotes, or unquoted keys.
Fix: Use strict JSON—double-quoted keys and strings, no trailing commas.
Likely cause: Encrypted token (JWE) or not a three-part JWT.
Fix: Confirm header.payload.signature shape; decrypt JWE in your auth stack.
Likely cause: Different regex engines or flags.
Fix: Match engine (JS vs PCRE) and flags to your runtime.
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Yes—free with no signup and no usage limits on this hub.
No. Tools run in your browser; payloads stay on your device.
Yes for debugging inspection. Decoding does not verify the signature—treat claims as untrusted until your backend validates.
Base64URL is URL-safe (+/ → -_) and used in JWTs. Pick the decoder matching your data.
JS allows trailing commas and single quotes; strict JSON does not.
UUID v4 (random) for most IDs. v1 or v5 only when you need those properties.
Use Timestamp Converter—check 10-digit seconds vs 13-digit milliseconds.
Validator finds syntax errors; Formatter prettifies valid JSON. Validate first when unsure.
Yes in modern mobile browsers—best for quick inspection; desktop for long payloads.
SHA-256 or SHA-512 for integrity; MD5/SHA-1 only for legacy non-security checks.
Free Online Developer Tools — JSON, Regex, JWT & More (/developer-tools) runs in your browser when supported—inputs are not uploaded to EverydayTools servers.
Formatting and decoding follow standard specs (JSON, JWT/Base64URL, UUID). JWT decode does not verify signatures.
For security-critical work, follow your organization's policies; verify tokens and secrets in production tooling.
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Reviewed by EverydayTools Editorial Team on 2026-05-20.
Same workflow or intent — pick the next step without leaving the site.
Compare two JSON documents structurally—highlight added, removed, and changed paths. Ignore noisy fields, export RFC 6902 patch or merge patch. Runs in your browser.
Paste JSON and see syntax errors with line and column numbers. Auto-validate in your browser—fix trailing commas and comments locally. No upload, no signup.
Free regex tester — highlight matches, capture groups, flags, and replace preview. JavaScript RegExp in your browser; patterns and text stay on your device, nothing uploaded.
Decode JWT header and payload, check exp/iat claims, encode HS256 test tokens. No upload—runs in your browser locally. Free, no signup.
Free UUID generator: v4, v7 & v1 GUIDs in your browser—bulk up to 1,000, validate, export JSON/CSV. crypto.randomUUID; never uploaded.
Compute MD5, SHA-1, SHA-256 and other digests from text locally. One-way hashing for checksums—not password storage.
Cross-category tools others open in the same session.
What is 20% of 500? Percent increase, decrease, difference, reverse %, markup & margin—runs locally in your browser, no upload. Copy results or share a link.
Free JSON formatter — paste minified or messy JSON and instantly get beautified, indented output with syntax highlighting and error detection. Browser-based, no server upload. Runs locally in your browser when supported—no upload required for normal use.
Free word counter — live word, sentence, and paragraph counts plus reading time for essays, blogs, and SEO drafts. Runs locally in your browser.
Free adult BMI from height and weight (lb/ft/in or kg/cm). CDC category, healthy weight range, optional waist. Screening only—runs in your browser.
Format JSON, test regex, decode JWTs, generate UUIDs, and run daily dev tasks in your browser. Tokens and payloads never leave your device.
Browser-based developer tools format, validate, decode, and generate dev data—JSON, regex, JWT, UUID, timestamps, Base64—instantly without installing software or uploading payloads to a server.
Developer tools solve small, repetitive tasks during debugging, code review, and API work: prettify a minified JSON response, test a regex before shipping it, decode a JWT to check expiry, or generate UUIDs for seed data.
EverydayTools runs these utilities in your browser with JavaScript. Tokens, API keys, and payloads are processed locally—they are not uploaded to EverydayTools servers. Copy results straight into your IDE, PR, or incident notes.
This hub groups JSON, regex, JWT, encoding, URL, cron, and hash tools so you can pick the right utility in one place.
Free JSON diff & compare — structural side-by-side diff, ignore paths, array modes, RFC 6902 patch and merge patch export. Runs locally in your browser—no upload.
Free UUID generator: v4, v7 & v1 GUIDs in your browser—bulk up to 1,000, validate, export JSON/CSV. crypto.randomUUID; never uploaded.
Free random number generator — Web Crypto integers or decimals, no-repeat draws, dice, coin flip, and list picker. Copy or CSV. Runs locally in your browser.
Free .env file parser — paste any .env file and extract all environment variables as structured JSON or YAML. Useful for config migration and debugging. No signup needed. Runs locally in your browser when supported—no upload required for normal use.
Free .env file parser — paste any .env file and extract all environment variables as structured JSON or YAML. Useful for config migration and debugging. No signup needed. Runs locally in your browser when supported—no upload required for normal use.
Generate a secure random API key or webhook secret in your browser. Hex, Base64url, or alphanumeric. Keys stay local—not a Stripe or OpenAI credential.
Design a mock REST response in your browser—JSON body, status, headers, and delay. Copy Express or MSW snippets. Free, no signup. Does not host a live API URL.
Free number base converter: binary, decimal, octal, hex, and custom bases 2–36. Live convert with BigInt for large integers. Browser-local, no signup.
Encode text to Base64 or decode a Base64 string online. UTF-8 safe, with URL-safe Base64. Runs in your browser—no upload, no signup.
See your browser name and version in one second—plus OS, screen size, and user agent. Copy for support; runs locally with nothing uploaded.
Minify or beautify HTML, CSS, and JavaScript in your browser with UTF-8 size comparisons, copy, and download. No source upload.
Pick a color and copy HEX, RGB, HSL, or CSS. Sample the screen or an image in your browser — no signup and no image upload.
Paste a blocked-by-CORS-policy error or generate Access-Control headers for HTTP, Nginx, Express, and Next.js.
Build cron schedules with live preview, timezone next runs, and platform snippets for Linux, Quartz, K8s, GitHub Actions & AWS. Browser-local.
Format CSS with consistent indentation and line breaks. Local beautification for readable stylesheets and git diffs. Runs locally in your browser when supported—no upload required for normal use.
Convert a cURL command into JavaScript fetch() code in your browser. Headers, JSON, forms, and auth stay on your device.
Extract deduplicated domains from logs, emails, and mixed text. URLs, markdown, hostnames. CSV/JSON export. No upload—100% browser-based.
Free Git commit message generator — build Conventional Commits (feat, fix, chore, docs, refactor) with scope, breaking change flag, and body. Copy the formatted message instantly. No signup. Runs locally in your browser when supported—no upload required for normal use.
Free GraphQL formatter — paste queries, mutations, or schema definitions and instantly get properly indented, beautified output with syntax validation. Perfect for debugging. No signup. Runs locally in your browser when supported—no upload required for normal use.
Compute MD5, SHA-1, SHA-256 and other digests from text locally. One-way hashing for checksums—not password storage.
Free HTML entity encoder—convert &, <, >, and quotes to &, <, > and decode entities back. XSS-safe for templates. Runs locally in your browser; no upload.
Format, beautify, or minify HTML with 2 spaces, 4 spaces, or tabs. Runs in your browser. Nothing is uploaded.
Parse Cookie and Set-Cookie headers, decode values, inspect attributes, and build Set-Cookie strings in your browser.
Build HTTP request and response headers and copy them as raw HTTP, cURL, Fetch, JSON, Nginx, Apache, or Express. Free and browser-based.
Free IPv4 converter — dotted decimal, 32-bit integer, hex, and binary octets from one paste. Batch CSV export. Runs in your browser. No signup.
Free JSON diff & compare — structural side-by-side diff, ignore paths, array modes, RFC 6902 patch and merge patch export. Runs locally in your browser—no upload.
Free JSON formatter — paste minified or messy JSON and instantly get beautified, indented output with syntax highlighting and error detection. Browser-based, no server upload. Runs locally in your browser when supported—no upload required for normal use.
Find JSON paths and test JSONPath expressions in your browser. Click a value, copy the path, or query nested JSON with wildcards and filters.
Free JSON Schema generator — infer Draft 2020-12 from sample JSON with TypeScript, Zod, Yup, and OpenAPI exports. No signup. Runs locally in your browser—no upload required.
Validate JSON syntax and find errors instantly. Get clear error messages with line and column details. Runs locally in your browser when supported—no upload required for normal use.
Decode JWT header and payload, check exp/iat claims, encode HS256 test tokens. No upload—runs in your browser locally. Free, no signup.
Create and sign JWT tokens online with HS256, HS384, or HS512. Custom claims, expiry presets, browser-only HMAC for development and API testing.
Free localStorage viewer: search keys, JSON preview, edit, export, and bulk delete for this origin. Runs locally in your browser—never uploaded.
Free online Markdown editor — write Markdown with syntax highlighting and see the rendered HTML preview in real time. Export as HTML or copy formatted output. No signup required. Runs locally in your browser when supported—no upload required for normal use.
Free QR code generator — create scannable QR codes from URLs, plain text, email, phone numbers, or Wi-Fi credentials. Download as PNG or SVG. No signup, no limits, fully browser-based. Runs locally in your browser when supported—no upload required for normal use.
Parse a full URL or query string into decoded key-value parameters. Inspect repeated keys, copy JSON, and debug URL parameters in your browser—no signup.
Free random number generator — Web Crypto integers or decimals, no-repeat draws, dice, coin flip, and list picker. Copy or CSV. Runs locally in your browser.
Free regex tester — highlight matches, capture groups, flags, and replace preview. JavaScript RegExp in your browser; patterns and text stay on your device, nothing uploaded.
Free screen resolution checker — instantly see your screen resolution, viewport size, device pixel ratio (DPR), and current CSS breakpoint. Useful for responsive design testing. No signup. Runs locally in your browser when supported—no upload required for normal use.
Free semver calculator — compare two version strings, bump major, minor, or patch components, and sort version lists following SemVer 2.0 rules. Essential for npm, Cargo, and API release management. No signup. Runs locally in your browser when supported—no upload required for normal use.
Free semver range checker — test whether a version string (e.g. 2.3.1) satisfies a range expression (^2.0.0, >=1.5.0 <3.0.0, ~2.3.x) following npm / SemVer 2.0 rules. Useful before upgrading package dependencies. No signup. Runs locally in your browser when supported—no upload required for normal use.
Free SemVer format validator — check whether a version string follows Semantic Versioning 2.0 (major.minor.patch with optional pre-release and build metadata). Catches leading zeros, missing patch components, and invalid identifiers instantly. No signup. Runs locally in your browser when supported—no upload required for normal use.
Inspect, search, edit, and export sessionStorage for the current origin, or import a snapshot captured on another site. Runs in your browser.
Beautify or minify SQL in the browser. Dialect-aware formatting stays on your device.
Build SQL queries online with a visual builder: SELECT, JOIN, WHERE, GROUP BY, plus INSERT/UPDATE/DELETE. MySQL, PostgreSQL, SQLite, SQL Server. Browser-only—no execution.
Escape or unescape text for JSON, JavaScript, HTML, regex, SQL, CSV, and XML. Runs in your browser.
Compare two texts online: line, word, and character diffs, side-by-side or unified. Local files stay in your browser—not JSON structure.
Free text to binary converter — encode any text to 8-bit binary (0s and 1s) and decode binary back to text. Supports ASCII and UTF-8 encoding. Instant, browser-based, no signup. Runs locally in your browser when supported—no upload required for normal use.
UTF-8 byte hex, code point & Latin-1 modes, byte inspector, hex dump, binary/Base64 compare—browser-local with share URL.
Format and validate TOML online. Beautify Cargo.toml, pyproject.toml and other config files, catch syntax errors with line and column details, then copy or download instantly.
Free URL builder and UTM generator: add query parameters, preserve existing keys, auto-encode values, and copy tracking links in your browser.
Free URL encoder decoder for query values and full URLs—encodeURIComponent & encodeURI. Percent-encode or decode instantly in your browser; never uploaded.
Parse any URL into scheme, host, port, path, query params, and hash. No upload—runs in your browser. Free for API and OAuth debugging.
Parse any user agent string online to detect browser, OS, device, engine, CPU, bots, and reduced-UA notes. Free, private and browser-based.
Free UUID generator: v4, v7 & v1 GUIDs in your browser—bulk up to 1,000, validate, export JSON/CSV. crypto.randomUUID; never uploaded.
Free YAML formatter and validator — paste YAML to fix indentation, validate syntax, and detect errors instantly. Supports YAML 1.2. Perfect for Docker Compose and Kubernetes manifests. No signup. Runs locally in your browser when supported—no upload required for normal use.
Free YAML formatter and validator — paste YAML to fix indentation, validate syntax, and detect errors instantly. Supports YAML 1.2. Perfect for Docker Compose and Kubernetes manifests. No signup. Runs locally in your browser when supported—no upload required for normal use.
Free UUID generator: v4, v7 & v1 GUIDs in your browser—bulk up to 1,000, validate, export JSON/CSV. crypto.randomUUID; never uploaded.
Parse any user agent string online to detect browser, OS, device, engine, CPU, bots, and reduced-UA notes. Free, private and browser-based.
Parse any URL into scheme, host, port, path, query params, and hash. No upload—runs in your browser. Free for API and OAuth debugging.
Free URL encoder decoder for query values and full URLs—encodeURIComponent & encodeURI. Percent-encode or decode instantly in your browser; never uploaded.
Free URL builder and UTM generator: add query parameters, preserve existing keys, auto-encode values, and copy tracking links in your browser.
Free developer tools format JSON, test regex, decode JWTs, generate UUIDs and API keys, and convert timestamps—all locally in your browser with no server upload.
Pick a tool, paste your input, and copy the result in seconds.
No signup · Local processing · 100% free