TOOL TOPIC
Web developer tools
Inspect, format, convert, and generate common web-development data without opening a separate development environment.
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Common tasks in this topic
Utilities for URLs, HTTP, JSON, HTML, CSS, JWT, regex, hashes, UUIDs, Markdown, SQL, and other everyday web-development tasks.
1
Parse URLs and HTTP requests
2
Format JSON, XML, HTML, SQL, and code
3
Inspect JWTs, regex patterns, hashes, and UUIDs
Tools in this topic
Choose the tool that most closely matches the task you need to finish.
JSON Schema generator from sample JSONInfer a Draft-07-compatible JSON Schema from sample JSON, then copy or download it.Use →DMARC record generatorBuild a DMARC DNS TXT record from policy, aggregate-report address, percentage, and alignment settings.Open →SPF record generatorBuild an SPF TXT value from sending IPs, include domains, a/mx mechanisms, and an all policy.Open →CAA record generatorGenerate CAA record lines for permitted certificate authorities and optional iodef reporting.Open →DNS TXT record formatterSplit long TXT values into 255-character chunks and format them for DNS configuration.Open →llms.txt generatorDraft an llms.txt file from a site name, summary, and key pages. It is guidance metadata, not access control.Open →AI crawler robots.txt generatorGenerate robots.txt blocks for selected AI crawler user agents with allow or disallow rules.Open →X-Robots-Tag generatorBuild an X-Robots-Tag HTTP header value from noindex, nofollow, nosnippet, and preview directives.Open →HSTS header generatorBuild a Strict-Transport-Security header from max-age, includeSubDomains, and preload options.Open →URL parser onlineParse a URL into protocol, host, port, path, query parameters and fragment.Open →HTTP request parser onlineParse a raw HTTP request into request line, headers and body without sending it.Open →Regex tester onlineTest JavaScript regular expressions with flag checkboxes, highlighted matches, indexes, capture groups, named groups, and replacement previews.Open →URL encoder / decoderPercent-encode or decode URL text.Open →JSON formatter / validatorFormat or minify JSON, locate syntax errors by line and column, choose indentation, optionally sort keys, inspect structure metrics, and copy or download the result.Open →Base64 encoder / decoderEncode or decode Unicode text as Base64.Open →UUID v4 / v7 generatorGenerate UUID v4 values in your browser.Open →SHA hash generatorGenerate SHA-256 / 384 / 512 hashes locally in your browser.Open →Password generatorGenerate random passwords locally with chosen character sets.Open →URL slug generatorTurn a title or phrase into a URL-friendly slug.Open →CSS clamp() generatorGenerate a fluid CSS clamp() expression from viewport and size ranges.Open →mailto link builderGenerate a mailto link from recipient, subject and body.Open →URL query parserParse URL query parameters into a readable list.Open →TOTP generator (2FA code)Generate TOTP codes locally from a Base32 secret or otpauth:// URI.Open →JWT decoderDecode JWT header and payload locally. Signature is not verified.Open →JSON key sorterRecursively sort JSON object keys alphabetically.Open →JSON array deduplicatorRemove duplicate values/objects from a JSON array.Open →XML formatterFormat and validate XML in the browser.Open →Markdown table generatorGenerate a Markdown table from tab- or comma-separated rows.Open →Edit HTML and Preview the Browser ResultEdit HTML and preview the rendered browser result.Open →Format Minified HTML with Lines and IndentationAdd line breaks and indentation to compressed HTML.Open →Format One-line SQL with Readable Line BreaksFormat one-line SQL into a more readable layout.Open →Minify CSS, JavaScript, or HTMLCreate a smaller copy of CSS, JavaScript, or HTML.Open →Preview How Markdown Will RenderEnter Markdown and check how it will render.Open →Encode or Decode HTML EntitiesEncode special HTML characters or restore entity references.Open →Inspect Unicode Code Points for TextInspect Unicode code points for text, symbols, and emoji.Open →Convert Text, Binary, Decimal Bytes, and HexConvert between text and binary, decimal, or hexadecimal bytes.Open →QR Code GeneratorCreate a QR code from a URL or text in your browser, export PNG/SVG, and verify it by re-scanning.Open →Logo QR Code MakerCreate a QR code with a centered logo or illustration, export PNG/SVG, and re-scan it in your browser.Open →Design QR Code MakerCreate a styled QR code with custom dots, colors and gradients, export PNG/SVG, then verify it by re-scanning.Open →QR Code Test — Scannability CheckerTest a QR image at full size, reduced size, lower contrast and light blur before publishing or printing.Open →JSON diff checkerCompare two JSON values and list added, removed, and changed paths.Open →JSON Schema validatorValidate JSON data against a JSON Schema (Draft-07 style) and show errors.Open →JSONPath testerRun common JSONPath expressions against JSON and inspect matched values.Open →JSON ↔ YAML converterConvert between JSON and YAML and check syntax errors.Open →Cron expression builder / parserBuild and validate 5-field cron expressions with presets, a human-readable explanation, dialect notes, and a preview of the next five run times.Open →User-Agent parserEstimate browser, operating system, and device type from a User-Agent string.Open →CIDR / subnet calculator (IPv4 & IPv6)Calculate normalized IPv4/IPv6 CIDR ranges, first/last addresses and total size.Open →IP range to CIDR converterConvert a start/end IP range into the smallest exact CIDR list.Use →TITLE / META length checkerCheck title and meta description character counts, UTF-8 bytes, and recommended ranges.Open →SERP previewPreview how a title, URL, and description may look in a search result.Open →vCard QR code generatorCreate a vCard QR code from name, organization, phone, email, and URL fields.Open →Meta tag generatorGenerate basic title, description, robots, and viewport tags.Open →Open Graph / OGP previewPreview a social Open Graph card from title, description, URL, and image URL.Open →Open Graph tag generatorGenerate Open Graph tags including title, description, URL, image, and card type.Open →Canonical tag generatorGenerate a canonical link tag from an absolute canonical URL.Open →hreflang tag generatorGenerate hreflang and x-default tags from language-code and URL pairs.Open →robots.txt generatorBuild a robots.txt file from user-agent, allow, disallow, and sitemap settings.Open →XML sitemap generatorGenerate an XML sitemap from URLs with optional lastmod, changefreq, and priority.Open →JSON-LD formatter / basic validatorFormat or minify JSON-LD and check basic @context and @type structure.Open →Wi-Fi QR code generatorCreate a Wi-Fi connection QR code from SSID, security type, and password.Open →Email QR code generatorGenerate a QR code that opens a prefilled email draft.Open →Phone QR code generatorGenerate a QR code for dialing a phone number.Open →SMS QR code generatorGenerate a QR code for an SMS recipient and message.Open →Location QR code generatorGenerate a QR code from latitude and longitude coordinates.Open →Event / calendar QR code generatorGenerate a QR code containing a calendar event.Open →QR code image readerRead the content of a QR code image in your browser.Open →Barcode generatorGenerate Code128, EAN-13, UPC-A and other barcodes in your browser.Open →Barcode readerDetect and read supported barcodes from an image using browser APIs.Open →Twitter / X Card tag generatorGenerate Twitter/X Card meta tags from page information.Open →robots.txt syntax checkerCheck common directives and basic syntax in a pasted robots.txt file.Open →XML Sitemap syntax checkerCheck XML syntax and basic URL entry structure in an XML sitemap.Open →FAQ Schema generatorGenerate FAQPage JSON-LD from question-and-answer pairs.Open →Breadcrumb Schema generatorGenerate BreadcrumbList JSON-LD from labels and URLs.Open →Favicon HTML tag generatorGenerate favicon, apple-touch-icon, and manifest link tags.Open →Web App Manifest generatorGenerate a PWA manifest.webmanifest file from form fields.Open →PWA manifest validatorValidate required and recommended fields in a Web App Manifest JSON.Open →Query string builderBuild and parse URL query strings from key-value pairs.Open →MIME type lookupLook up common MIME types by extension or MIME value.Open →HTTP status code lookupLook up HTTP status code meanings and categories.Open →Punycode converterConvert internationalized domain names between Unicode and Punycode.Open →Data URI generator / parserGenerate Data URIs from text/files and parse Data URIs.Open →Markdown to HTML converterConvert Markdown to HTML in the browser with source output and a safe preview.Open →JSON flattenerFlatten nested JSON into dot-separated key paths.Open →JSON unflattenerRebuild nested JSON from dot-separated flat keys.Open →JSON to TypeScript interfaceInfer TypeScript interfaces/types from a JSON sample.Open →JSON Pointer testerResolve values in JSON with RFC 6901 JSON Pointer.Open →CSV to XML converterConvert CSV rows and columns into XML in the browser.Open →XML to CSV converterConvert repeated XML elements into tabular CSV.Open →XML to JSON converterConvert XML to JSON while preserving attributes and text.Open →JSON to XML converterConvert JSON into XML with a custom root element.Open →URI component encoder / decoderEncode or decode URI components in the browser.Open →Bulk UUID v4 / v7 generatorGenerate multiple UUID v4 values with case and hyphen options.Open →Random string generatorGenerate random strings with configurable length, count, and character sets.Open →JWT expiry checkerDecode JWT exp, nbf, and iat claims and inspect time validity.Open →CSP header builderBuild a Content-Security-Policy header from common directives.Open →Permissions-Policy builderBuild a Permissions-Policy header for browser features.Open →Cache-Control header builderBuild Cache-Control directives including max-age and immutable.Open →CORS header builderBuild example CORS response headers from origin and method settings.Open →Referrer-Policy builderChoose and generate a Referrer-Policy header.Open →security.txt generatorGenerate security.txt fields for RFC 9116 deployment.Open →.htaccess redirect generatorGenerate Apache .htaccess 301/302 redirect rules.Open →nginx redirect generatorGenerate nginx 301/302 redirect rules.Open →chmod permission calculatorConvert three-digit chmod values to rwx permission notation.Open →Semantic version comparatorCompare two Semantic Version 2.0.0 values.Open →Relative URL resolverResolve a relative URL against a base URL using browser URL rules.Open →SRI hash generatorGenerate sha256/384/512 Subresource Integrity hashes for text or files.Open →HTTP header parserParse raw HTTP headers into names and values and flag duplicate fields.Use →Cookie header parserParse a Cookie header into key-value pairs with optional URL decoding.Use →dotenv parserParse KEY=VALUE dotenv text, validate variable names, and convert it to JSON.Use →Authorization header builderBuild Basic or Bearer Authorization headers locally in your browser.Use →Regex escape toolEscape plain text so it can be safely used as a regex literal.Use →SQL IN list builderBuild a SQL IN (...) list from one value per line.Use →CSS specificity calculatorCalculate CSS selector specificity as ID, class/attribute/pseudo-class, and element components.Open →CSS unit converterConvert px, rem, em, vw, and vh using configurable font and viewport dimensions.Open →HTTP Date converterConvert dates between HTTP Date (RFC 7231), ISO 8601, and Unix seconds.Open →IP address validator & normalizerValidate and normalize IPv4/IPv6 addresses and common special-purpose ranges.Open →MAC address formatter & validatorValidate a MAC address and format it with colons, hyphens, or Cisco-style dots.Open →UUID validator / version inspectorValidate a UUID and report its version and RFC variant bits.Open →ULID generatorGenerate sortable 26-character ULIDs locally in your browser.Open →cURL to fetch converterConvert a common curl command into browser fetch() code.Open →fetch to cURL builderBuild a reusable curl command from URL, HTTP method, headers, and request body.Open →Accept-Language parserParse an Accept-Language header into language tags and q-values sorted by preference.Open →YAML formatter and validatorValidate and format YAML, with an optional JSON preview.Open →INI to JSON converterConvert between INI configuration text and JSON while preserving sections and key/value pairs.Open →JSON Merge Patch toolApply an RFC 7396 JSON Merge Patch to a target JSON document.Open →JSON array sort by keySort a JSON array by a selected key path in ascending or descending order.Open →Content-Type parserParse a Content-Type header into media type, charset, boundary, and other parameters.Open →Accept header parserParse an HTTP Accept header into media ranges and q-values sorted by preference.Open →Content-Disposition parserParse a Content-Disposition header into disposition, name, filename, and filename* parameters.Open →URL query parameter sorterSort URL query parameters by key/value and optionally remove common tracking parameters.Open →HTML table to CSV converterExtract an HTML table and convert it to CSV.Open →Base64URL encoder / decoderConvert UTF-8 text to and from URL-safe Base64.Open →PKCE verifier / challenge generatorGenerate OAuth 2.0 PKCE code_verifier and S256 code_challenge locally.Open →URL normalizerNormalize URLs, remove common tracking parameters, and sort query parameters.Open →NDJSON / JSON array converterConvert between newline-delimited JSON (NDJSON/JSONL) and JSON arrays.Open →URL query parameter diffCompare query parameters between two URLs and identify additions, removals, and changes.Open →HTTP cache freshness calculatorEstimate HTTP cache freshness remaining from Date, Age, and max-age.Open →SQL test data generatorGenerate batches of SQL INSERT statements from simple column type definitions.Open →
Related guides
Use these when you need the decision context around the tools.
HSTS, CSP, CORS and Cache-Control: different responsibilitiesReview decisions, failure points and workflow context.Read →robots.txt, llms.txt, and X-Robots-Tag for AI crawlersReview decisions, failure points and workflow context.Read →How SPF, DKIM, DMARC, and CAA fit togetherReview decisions, failure points and workflow context.Read →robots.txt, noindex, sitemap and canonical are not interchangeableReview decisions, failure points and workflow context.Read →JSON or regex failing? Split “is it valid?” from “does it do what I meant?”Review decisions, failure points and workflow context.Read →Why the same cron expression can behave differentlyReview decisions, failure points and workflow context.Read →Before you publish: check the domain, hosting, and HTTPSReview decisions, failure points and workflow context.Read →
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Related references
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