Developer Tools for HTTP, Regex, URLs, and Everyday Debugging
These tools answer implementation questions that are small enough to isolate but important enough to derail debugging: what a raw request contains, how a regex matched, what changed between header sets, how a URL was parsed, or which parts of a cURL command a browser Fetch request cannot reproduce exactly.
Start from the Artifact in Front of You
Similar-looking inputs can require different operations. Choosing the operation first avoids turning a formatter, parser, builder, or tester into something it was never meant to prove.
Raw HTTP or cURL: parse first when you need method, target, headers, cookies, body, authentication, or framing separated into inspectable pieces.
Values you are constructing: use builders for headers, query strings, authentication, Accept values, or commands when the desired pieces are already known.
Behavior you want to observe: use regex testers, method comparisons, cache analysis, or header diffs when the question is about a defined behavior rather than text shape.
One syntax translated to another: review the conversion notes because cURL, Fetch, shells, and browsers do not share identical redirect, credential, quoting, or networking semantics.
Representative Debugging Paths
These six tools are deliberately selected to represent request parsing, regex work, syntax translation, URL inspection, cache reasoning, and API error analysis rather than simply showing the first items in the registry.
Regex Match Tester
Run JavaScript regex patterns with selected flags, capture groups, UTF-16 indexes, and replacement behavior.
Open tool →HTTP Request Parser
Parse raw HTTP/1.x requests into URLs, headers, query data, cookies, bodies, JSON, or cURL.
Open tool →Fetch to cURL Converter
Convert supported literal fetch() requests into POSIX-shell cURL commands with safe quoting and optional secret masking.
Open tool →URL Parts Parser
Resolve and parse absolute or relative URLs while preserving duplicate parameters and masking embedded credentials.
Open tool →API Error Response Formatter
Separate HTTP status, app codes, validation details, trace IDs, and RFC 9457 fields from API error responses.
Open tool →HTTP Cache Header Analyzer
Interpret Cache-Control, ETag, Expires, Last-Modified, Vary, Age, TTL, and revalidation signals from response headers.
Open tool →All Developer Tools
Browse all 29 tools for HTTP text, APIs, headers, URLs, regex, timestamps, UUIDs, query strings, cURL, Fetch, GraphQL, and related implementation work.
Word Counter
Count words, grapheme clusters, sentences, and reading time using locale-sensitive browser text segmentation.
UUID Generator
Generate RFC 9562 UUIDv4 identifiers locally from cryptographically secure browser randomness.
CURL Command Builder
Build curl commands with POSIX-shell-safe quoting for methods, URLs, headers, and request bodies.
Cookie Parser
Split Cookie header text into name-value pairs and percent-decode each parsed value.
MIME Type Finder
Match known file extensions to MIME media types and show the associated content type.
IP Address Inspector
Inspect IPv4 or IPv6 syntax and report the address form without performing network lookups.
UUID Validator
Check UUID structure, version, variant, Nil, Max, and reserved forms against RFC 9562.
Unix Timestamp Generator
Generate Unix seconds or milliseconds from dates, then convert timestamps back using an explicitly selected unit.
CURL to Fetch Converter
Convert cURL requests into browser fetch() code and flag headers or options Fetch cannot reproduce.
HTTP Request Formatter
Inspect HTTP/1.x request framing, target forms, headers, body bytes, and protocol warnings.
HTTP Response Formatter
Format raw HTTP responses and inspect status codes, headers, cookies, redirects, and body data.
HTTP Header Diff Checker
Compare two sets of HTTP headers and find added, removed, changed, or unchanged header values.
Regex Match Tester
Run JavaScript regex patterns with selected flags, capture groups, UTF-16 indexes, and replacement behavior.
HTTP Request Parser
Parse raw HTTP/1.x requests into URLs, headers, query data, cookies, bodies, JSON, or cURL.
SQL Beautifier / Minifier
Beautify or minify SQL while preserving quoted text, comments, dollar-quoted strings, and comparison operators.
cURL Command Parser
Parse cURL commands into method, URL, headers, authentication, cookies, and request body without losing duplicate headers.
Fetch to cURL Converter
Convert supported literal fetch() requests into POSIX-shell cURL commands with safe quoting and optional secret masking.
Query String Builder
Build query strings with duplicate keys, controlled percent encoding, and repeated, bracket, or comma array formats.
URL Parts Parser
Resolve and parse absolute or relative URLs while preserving duplicate parameters and masking embedded credentials.
Request Header Builder
Build HTTP request headers with auth helpers, secret masking, Fetch/CORS checks, and cURL or JSON output.
API Error Response Formatter
Separate HTTP status, app codes, validation details, trace IDs, and RFC 9457 fields from API error responses.
Regex Replace Tester
Preview JavaScript regex replacements with numbered or named captures, replacement tokens, match positions, and changed lines.
HTTP Cache Header Analyzer
Interpret Cache-Control, ETag, Expires, Last-Modified, Vary, Age, TTL, and revalidation signals from response headers.
API Rate Limit Header Parser
Interpret RateLimit draft fields, Retry-After, and provider-specific X-RateLimit quotas without guessing ambiguous reset timing.
HTTP Accept Header Generator
Build Accept, Content-Type, Accept-Language, and Accept-Encoding headers with q-value checks and browser Fetch restrictions.
Content-Disposition Header Generator
Build download or inline headers with ASCII fallback and RFC 8187 UTF-8 filenames.
GraphQL Query Formatter
Reformat GraphQL documents while preserving strings, comments, operations, variables, and request semantics.
HTTP Basic Auth Header Generator
Encode user-id and password bytes into RFC 7617 Basic Authorization headers and request snippets.
HTTP Method Tester
Compare HTTP method semantics and build cURL or fetch examples without sending requests.
Text Inspection Stops Where the Live Exchange Begins
A pasted request or response is a representation of an exchange, not the connection itself. TLS negotiation, redirects before or after the captured message, proxy rewriting, compression, browser CORS rules, authentication state, and intermediary caches can all change what happens on the network.
That distinction is especially important for converters. A generated Fetch or cURL example can preserve method, headers, and body while still differing at runtime because the two clients expose different controls. The useful result is a transparent translation with limitations, not a claim that two execution environments are identical.
Primary References
RFC 9110 defines HTTP semantics, including methods, status codes, fields, and representation concepts used across the HTTP tools.
MDN Fetch API documentation explains browser Fetch behavior and the restrictions that matter when translating command-line requests.
RFC 9562 defines the UUID formats and variants used by the UUID generator and validator.