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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.
More free tools for the same workflow.
Free JSON diff tool — compare two JSON objects side by side and instantly highlight added, removed, and changed keys. Ideal for debugging API responses and config changes. Runs locally in your browser when supported—no upload required for normal use.
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.
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Reviewed by EverydayTools Editorial Team on 2026-05-20.
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 cryptographically secure random API keys in hex, base64, or alphanumeric format — instantly in your browser with no upload, no signup.
Free API mock generator — create realistic mock API responses with custom status codes, response headers, and JSON body. Perfect for frontend development and testing. No signup. Runs locally in your browser when supported—no upload required for normal use.
Free number base converter — convert between binary (base 2), octal (base 8), decimal (base 10), hexadecimal (base 16), and text in real time. No signup required. Runs locally in your browser when supported—no upload required for normal use.
Free Base64 encoder and decoder — encode any text or data to Base64 and decode Base64 strings back to readable text. Supports URL-safe Base64 variant. No signup needed. Runs locally in your browser when supported—no upload required for normal use.
Free browser info checker — see user agent, screen size, viewport, DPR, language, and timezone instantly in your browser. Nothing is uploaded; data stays on your device.
Free code minifier and beautifier — minify JavaScript, HTML, and CSS for production or beautify minified code for readability. Supports ES6+ and modern CSS syntax. No signup. Runs locally in your browser when supported—no upload required for normal use.
Free online color picker — choose any color and instantly get HEX, RGB, HSL, HSB, and CMYK values. Copy color codes for CSS, design tools, and development. No signup. Runs locally in your browser when supported—no upload required for normal use.
Free CORS header generator — configure Access-Control-Allow-Origin, methods, headers, and credentials. Preview the full CORS response header block instantly. No signup. Runs locally in your browser when supported—no upload required for normal use.
Build and parse five-field cron expressions with human-readable descriptions and next-run previews. Runs locally in your browser when supported—no upload required for normal use.
Free cron parser — paste any cron expression and get a plain-English description of when it runs, plus the next 10 scheduled execution times. No signup required. Runs locally in your browser when supported—no upload required for normal use.
Free cron expression tester — validate cron syntax and preview the next scheduled run times in your timezone. Catch errors before deploying to production. No signup. Runs locally in your browser when supported—no upload required for normal use.
Free crontab generator — build cron schedule expressions for Linux servers, CI/CD pipelines, and automation. Supports all 5-field and 6-field cron formats. No signup. Runs locally in your browser when supported—no upload required for normal use.
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.
Free cURL to fetch converter — paste any cURL command and instantly get the equivalent JavaScript fetch() code with all headers, methods, and body included. No signup needed. Runs locally in your browser when supported—no upload required for normal use.
Extract deduplicated domains from logs, emails, and mixed text. URLs, markdown, hostnames. CSV/JSON export. No upload—100% browser-based.
Free email domain extractor — paste a list of email addresses and instantly extract the unique domain names with deduplication and normalization. No signup required. Runs locally in your browser when supported—no upload required for normal use.
Free URL domain extractor — paste a list of URLs and instantly extract the root domain from each. Normalizes www, strips paths and query strings. No signup needed. Runs locally in your browser when supported—no upload required for normal use.
Paste notes, articles, or chat exports and get deduplicated website names (example.com). Tidy whitespace, copy or .txt download. No upload—runs in your browser.
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.
Free HTML formatter—beautify minified markup with 2 or 4 space indent, minify for production. Runs locally in your browser; no upload or signup.
Paste any HTTP Cookie header, Set-Cookie header, or curl command to extract name, value, domain, path, expiry, Secure, HttpOnly, and SameSite flags. Build and export cookies too. No signup. Runs locally in your browser when supported—no upload required for normal use.
Free HTTP header generator — build Content-Type, Cache-Control, CORS, Authorization, and security headers with correct syntax. Copy for NGINX, Apache, or API responses. No signup. Runs locally in your browser when supported—no upload required for normal use.
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 tool — compare two JSON objects side by side and instantly highlight added, removed, and changed keys. Ideal for debugging API responses and config changes. Runs locally in your browser when supported—no upload required for normal use.
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 JSON path finder — click any value in a formatted JSON tree to instantly copy its JSONPath expression. Ideal for navigating deep API payloads and config files. No signup. Runs locally in your browser when supported—no upload required for normal use.
Free JSON Schema generator — paste sample JSON and instantly generate a JSON Schema Draft-7 with inferred types, required fields, and nested object definitions. No signup. Runs locally in your browser when supported—no upload required for normal use.
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 JSON Web Tokens (JWTs) online with HS256, HS384, or HS512. Enter header, payload, and secret to generate a signed JWT instantly — fully browser-based. Runs locally in your browser when supported—no upload required for normal use.
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.
Free query string parser — paste any URL query string and instantly extract all parameter key-value pairs into a readable JSON or table format. Handles URL encoding. No signup required. Runs locally in your browser when supported—no upload required for normal use.
Free random number generator — set a custom min and max range, choose quantity, and generate cryptographically random integers or decimals. Copy results instantly. No signup required. Runs locally in your browser when supported—no upload required for normal use.
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.
Free sessionStorage viewer — inspect, add, edit, and delete sessionStorage key-value pairs in your browser. Useful for debugging web apps and testing session data. No signup.
Format SQL with indented clauses and keyword casing. Dialect-aware beautification runs locally—not on a server.
Free visual SQL query builder — select table, columns, WHERE conditions, JOIN type, and ORDER BY using a form and get the generated SELECT query instantly. No signup required. Runs locally in your browser when supported—no upload required for normal use.
Free string escaper — escape or unescape strings for JavaScript, HTML, JSON, regex, and URL contexts with one click. Handles backslashes, quotes, newlines, and special characters. No signup. Runs locally in your browser when supported—no upload required for normal use.
Compare two plain-text inputs line by line and highlight changes. Local diff for logs and copy—not JSON structure. Runs locally in your browser when supported—no upload required for normal use.
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.
Free text to hex converter — encode text to hexadecimal format and decode hex strings back to readable text. Supports ASCII and Unicode. Uppercase/lowercase option. No signup. Runs locally in your browser when supported—no upload required for normal use.
Format and validate TOML config files like Cargo.toml and pyproject.toml instantly in your browser. Syntax highlighting, error detection, no upload required.
Free URL builder — add a base URL, append query parameters, auto-encode values, and copy the complete URL string. Perfect for API testing, UTM links, and affiliate tracking. No signup. Runs locally in your browser when supported—no upload required for normal use.
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.
Free user agent parser — paste any UA string and instantly identify the browser, version, operating system, device type, and rendering engine. No signup required. 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.
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 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