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Page Utils

Developer

Developer tools on Page Utils run in your browser with the Web Crypto, JSON, encoding, SQL, XML, CSS/HTML/JavaScript formatter, chmod permission, RGB↔CMYK conversion, line-diff, and Date/timestamp APIs your tab already loads. Live now: JWT Token Decrypt, JWT Token Generator, Password Generator, JSON Formatter, JSON Minify, UUID Generator, Base64 Decode, Cron Expression Generator, SQL Formatter, XML Formatter, CSS Formatter, HTML Formatter, HTML Minifier, JavaScript Formatter, YAML Formatter, JSON Schema Generator, Certificate Decoder, CSR Decoder, Flexbox Generator, Chmod Calculator, RGB to CMYK, Code Diff, and Timestamp to Date. Paste a token or blob, sign an HS256 JWT, generate a strong password, mint an id, draft a cron, pretty-print SQL, format XML, beautify CSS, HTML, or JavaScript, convert octal ↔ symbolic chmod, convert RGB ↔ CMYK, compare two pastes with a code diff, convert a Unix timestamp to date, or minify JSON or HTML — keys and query text stay in the tab and are never uploaded. XML Formatter, CSS Formatter, HTML Formatter, and JavaScript Formatter are whitespace-only (not JSON, not an XSD validator, not a Sass compiler, not a Markdown converter, not a bundler or terser). Chmod Calculator is local bitmask math only — it does not run chmod on a server. RGB to CMYK is a simple undercolour-removal formula — not an ICC press profile. Code Diff is a line-oriented LCS compare — not a git binary diff or merge tool. Timestamp to Date converts Unix seconds/milliseconds and ISO strings with honest unit detection — not a remote epoch API. JWT Token Generator creates and signs compact HS256 JWS locally with Web Crypto — it is not a jwt.io-clone decoder and not a JWE encryptor. Password Generator draws random passwords with crypto.getRandomValues and rejection sampling — it is not a vault and stores nothing. JSON Minify is the minify-first sibling of JSON Formatter. HTML Minifier is the minify-first sibling of HTML Formatter — layout-safe whitespace collapsing, comment controls, and byte stats; not Terser. YAML Formatter tidies and validates YAML with line/column errors — not a converter. JSON Schema Generator infers a JSON Schema from a JSON sample — inference only, not a validator. CSR Decoder reads PKCS#10 requests and requested SANs locally — decode only, not a CSR generator, signer, CA submission, or ownership check. Flexbox Generator builds a CSS flex layout with a live preview and copies CSS or Tailwind classes — not a page builder or a CSS Grid generator.

Which developer tools are live?

Questions about developer tools

Do you send my tokens or keys to a server?
No. Decrypt, JWT generate/sign, password generation, tidy, minify (JSON and HTML), encode, UUID, cron, SQL, XML, CSS/HTML/JavaScript format, chmod conversion, RGB↔CMYK conversion, code-diff, and timestamp-to-date steps use in-page JavaScript in this tab. There is no paste-bin, no account, and no key escrow. Tokens, keys, JSON, cron drafts, SQL text, XML, CSS, HTML, JavaScript source, permission modes, colour channel values, diff pastes, and timestamps stay in memory until you clear the form or close the tab. We do not write them to localStorage and we do not upload them to Page Utils servers.
Is JWT Token Decrypt a jwt.io clone?
No. jwt.io is built around inspecting and verifying signed JWTs (JWS). The live JWT Token Decrypt tool on this hub decrypts compact JWE — five-part encrypted tokens — using the Web Crypto API. If you paste a three-part signed JWT it is rejected with an explanation, not silently treated as encrypted. JWT Token Generator on this hub creates and signs compact HS256 tokens locally — it does not decode or verify arbitrary JWTs like jwt.io. Use jwt.io or a similar debugger when you need a full signature inspector.
Which algorithms does the JWE tool support today?
The playground reads alg and enc from the protected header. It supports dir with A128GCM or A256GCM, A256KW, and RSA-OAEP with a PKCS#8 PEM private key. Other JOSE algorithms are rejected with a clear error rather than guessed. Always match the key type to the header; a labelled FAKE example is on the page if you want to try the flow first.
Can I bookmark a country-specific developer URL?
There is one URL per tool, with a trailing slash, and no /in/ prefix. Use /developer/jwt-token-decrypt/, /developer/jwt-token-generator/, /developer/password-generator/, /developer/json-tidy/, /developer/json-minify/, /developer/uuid-generator/, /developer/base64-decode/, /developer/cron-expression-generator/, /developer/sql-formatter/, /developer/xml-formatter/, /developer/css-formatter/, /developer/html-formatter/, /developer/html-minifier/, /developer/javascript-formatter/, /developer/yaml-formatter/, /developer/json-schema-generator/, /developer/certificate-decoder/, /developer/csr-decoder/, /developer/flexbox-generator/, /developer/chmod-calculator/, /developer/rgb-to-cmyk/, /developer/code-diff/, and /developer/timestamp-to-date/ from India or anywhere else. We do not duplicate developer pages under a country path, because a second URL would split the canonical address search engines and people should share.
Does the UUID generator upload identifiers?
No. Version-4 UUIDs are minted with the Web Crypto API in this tab. Version-1 uses a timestamp and a random node, not a hardware MAC. Nothing is posted to Page Utils and nothing is written to localStorage. Close the tab to drop the list.
Does the base64 decode tool upload my paste?
No. Decode and encode run with TextDecoder and TextEncoder in this tab. There is no paste-bin and no account. Closing the tab drops the text. We do not write Base64 or plaintext to localStorage.
Which developer tools are live on Page Utils?
Twenty-three utilities are live: JWT Token Decrypt, JWT Token Generator, Password Generator, JSON Formatter, JSON Minify, UUID Generator, Base64 Decode, Cron Expression Generator, SQL Formatter, XML Formatter, CSS Formatter, HTML Formatter, HTML Minifier, JavaScript Formatter, YAML Formatter, JSON Schema Generator, Certificate Decoder, CSR Decoder, Flexbox Generator, Chmod Calculator, RGB to CMYK, Code Diff, and Timestamp to Date. Each runs in your browser. JSON Minify is the minify-first sibling of JSON Formatter — compact output by default, with optional Pretty to verify. Cron Expression Generator builds and reads a classic five-field expression — it does not host or fire jobs. SQL Formatter pretty-prints query text locally — it does not execute SQL against a database. XML Formatter pretty-prints or minifies XML with DOMParser — whitespace only, not JSON, and not an XSD/DTD validator. CSS Formatter pretty-prints or minifies CSS with a client-side CSS beautifier — whitespace only, not a Sass/Less compiler. HTML Formatter pretty-prints or minifies HTML with a client-side HTML beautifier — whitespace only, not a Markdown converter, and not a script runner. HTML Minifier shrinks HTML with layout-safe whitespace rules, comment controls (keeps Outlook conditional comments), and UTF-8 byte stats — not Terser and not a validator. YAML Formatter re-indents and validates YAML with line/column errors and optional key sorting — not a JSON↔YAML converter and not a Kubernetes schema checker. JSON Schema Generator infers a draft 2020-12 or draft-07 JSON Schema from a pasted JSON sample — inference only, not an OpenAPI generator and not a validator. Certificate Decoder reads PEM/DER X.509 certificates (subject, issuer, expiry, SANs, fingerprints) — decode only, not an SSL checker and not a chain validator. CSR Decoder reads PEM/DER PKCS#10 requests (subject, requested SANs, public key, attributes, SHA-256 fingerprint) — decode only, not a generator, signer, CA submission, or trust decision. Flexbox Generator sets container and per-item flex properties with a live preview and copies CSS, HTML, or Tailwind classes — a layout helper, not a page builder or CSS Grid generator. JavaScript Formatter pretty-prints or minifies JavaScript with Prettier (babel + estree) — whitespace only, not a bundler, not terser/uglify, and not a TypeScript type-checker. Chmod Calculator converts octal and symbolic Unix permission modes locally — it does not run chmod on a remote server. RGB to CMYK converts RGB 0–255 to CMYK percentages (and back) with a simple undercolour-removal formula — not an ICC press profile. Code Diff compares two pastes with a line-oriented LCS — not a git binary diff and not a merge tool. Timestamp to Date converts Unix seconds/milliseconds and ISO strings with honest unit detection — not a remote epoch API. JWT Token Generator creates and signs compact HS256 JWS with Web Crypto — not a jwt.io-clone decoder and not a JWE encryptor. Password Generator builds random passwords with crypto.getRandomValues — nothing is stored. Unshipped ideas are not given their own URLs, so this hub will not send you to a 404. Open any live tool from the list on this page.
Will the Cron Expression Generator schedule or run my job?
No. It only helps you draft and read a classic five-field cron expression in this browser tab. It does not connect to your server, install a crontab, host a scheduler, or fire commands. Copy the finished expression into the scheduler you control, then check that system's timezone and cron rules before relying on it.

What else can I open?