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Developer Data Tools site map.

A human-readable map of the main sections and required legal pages.

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Tools

Tool JSON Formatter & Validator

Format, minify, validate and debug JSON data with clear error feedback.

Tool JSON Compare

Compare two JSON documents, inspect structural differences and review API response changes without chasing formatting noise.

Tool Text Diff Checker

Compare text snippets, logs and configuration files to spot changed values, hidden whitespace and deployment differences.

Tool Regex Tester

Test JavaScript regular expressions against sample text, inspect matches and debug escaping, flags and multiline behavior.

Tool Base64 Encoder/Decoder

Encode and decode Base64 text in the browser for API payload fragments, Data URL examples and copied configuration values.

Tool URL Encoder/Decoder

Encode and decode URL components, query values and callback parameters while debugging browser and API requests.

Tool HTML Entity Encoder/Decoder

Escape and decode HTML entities safely for documentation snippets, copied API responses and template debugging.

Tool Timestamp Converter

Convert Unix timestamps and readable dates to compare seconds, milliseconds, UTC output and local browser display.

Tool Cron Expression Parser

Understand cron fields, common schedule examples, timezone assumptions and platform differences for scheduled jobs.

Tool Hash Generator

Generate common hashes for checksums, payload comparison, signing examples and debugging data integrity workflows.

Tool AES Encrypt/Decrypt

Test browser-based AES encryption workflows carefully while reviewing keys, IVs, metadata and sensitive data limits.

Tool User-Agent Parser

Parse user-agent strings into browser, engine, operating system and device hints for support and compatibility debugging.

References

Workflows

Workflow Why JSON.parse Fails After a Successful Fetch Request

Debug cases where fetch succeeds but JSON parsing fails because the body is empty, HTML, malformed, already consumed or not actually JSON.

Workflow Why an API Returns HTML Instead of JSON

Trace the common reasons an API client receives an HTML page instead of JSON, including redirects, expired sessions, proxy errors and wrong routes.

Workflow Why a 204 Response Breaks response.json()

Understand why No Content responses cause JSON parsing failures and how to handle empty success responses without hiding real API bugs.

Workflow Base64 Encoding Explained for API Payload Debugging

Learn how Base64 appears in API payloads, why it increases size, how to decode it safely and when it is the wrong transport choice.

Workflow URL Encoding in Query Strings: Practical API Examples

Debug broken query strings by checking reserved characters, spaces, plus signs, repeated parameters, nested URLs and encoding boundaries.

Workflow Unix Timestamp Seconds vs Milliseconds: The 1000x Bug

Debug date values that land decades in the past or future by checking whether an API timestamp uses seconds, milliseconds, UTC or local display formatting.

Workflow Why Content-Type Breaks JSON Parsing

Debug JSON requests and responses by checking Content-Type, Accept, charset, problem+json, form encoding and server middleware assumptions.

Workflow How to Debug CORS Preflight Failures

Work through CORS preflight failures by checking OPTIONS responses, allowed origins, requested headers, methods, credentials and proxy behavior.

Workflow Hashing vs Encryption in API Debugging

Avoid confusing hashes, encryption, signatures and encoding when inspecting tokens, payloads, checksums and stored secrets in API systems.

Workflow How Hidden Whitespace Breaks Configuration Values

Find invisible spaces, trailing newlines, tabs, non-breaking spaces and copied quote characters that break env vars, headers, tokens and config.

Workflow How to Compare API Responses Without Chasing Noise

Compare two API responses by separating meaningful schema changes from timestamps, ordering, request ids, formatting and environment-specific fields.

Workflow Why Webhook Signature Verification Fails

Debug webhook signature failures by preserving the raw body, checking timestamp headers, payload canonicalization, secret selection and encoding boundaries.

Workflow Why Regex Works in a Tester but Fails in JavaScript

Debug regex mismatches caused by escaping, flags, global state, multiline input, greedy patterns and real JavaScript strings.

Workflow Why Cron Jobs Run at the Wrong Time

Debug scheduled jobs by checking cron field order, timezone assumptions, day-of-week semantics, DST, server location and scheduler-specific syntax.

Workflow Why HTML Entities Show Up in API Responses

Debug escaped ampersands, quotes, angle brackets and double-encoded HTML entities that appear in JSON responses, rendered UI and copied API payloads.

Workflow How to Use User-Agent Data Without Breaking Feature Detection

Use user-agent strings as debugging context while avoiding brittle browser detection, spoofing assumptions and support flows that ignore feature checks.

Workflow How to Debug API Rate Limit 429 Responses

Debug HTTP 429 responses by checking retry headers, quota windows, user versus token limits, burst behavior, client retries and background traffic.

Workflow Why Cache-Control Makes API Responses Look Stale

Debug stale API responses by checking Cache-Control, ETag, 304 responses, browser cache, CDN rules, service workers and request cache options.

Workflow How to Debug Environment Variable Mismatches

Debug local, staging and production differences by comparing loaded environment variables, build-time values, runtime values and deployment scopes.

Workflow Why JSON with Comments or Trailing Commas Fails

Debug JSON copied from JavaScript, config files or documentation by removing comments, trailing commas, single quotes and other JSON5-style syntax.

Workflow Why Copied API Payloads Change After Pasting

Debug copied API payloads that change when moved through terminals, documents, chat tools, spreadsheets, browser DevTools or clipboard managers.

Workflow How to Debug API Request Body Too Large Errors

Debug 413 and payload size failures by checking body limits, proxy limits, Base64 overhead, compression, upload strategy and duplicated JSON fields.

Workflow Why multipart/form-data Uploads Fail

Debug file upload failures by checking boundaries, FormData construction, field names, file metadata, server parsers and accidental Content-Type overrides.

Workflow Why OAuth Redirect URI Mismatches Happen

Debug OAuth redirect_uri mismatch errors by comparing exact URLs, schemes, ports, trailing slashes, encoded paths and environment settings.

Workflow Why Decoding JWT Payloads Is Not Verification

Debug JWT issues by separating Base64URL decoding from signature verification, claim validation, algorithm checks, expiration and audience matching.

Workflow Why API Pagination Cursors Repeat or Skip Results

Debug cursor pagination by checking stable sort order, duplicate timestamps, cursor encoding, filters, page size, inserts and client retries.

Workflow Why API Sorting and Filtering Parameters Disagree

Debug list APIs where sort, filter, search and pagination parameters produce unexpected results because client and server interpret query values differently.

Workflow Why CSV Exports Break JSON Imports

Debug data moved from CSV to JSON by checking delimiters, quotes, encodings, newlines, numeric conversion, leading zeros and spreadsheet formatting.

Workflow Why Browser Storage Keeps Stale API Tokens

Debug stale browser tokens by checking localStorage, sessionStorage, cookies, service workers, multiple tabs, refresh timing and logout cleanup.

Workflow How to Debug Fetch Timeouts and AbortController

Debug browser fetch timeout behavior by separating network failure, AbortController cancellation, server latency, retries and UI race conditions.

Workflow Why Schema Validation Fails After JSON Is Valid

Debug the gap between valid JSON syntax and API schema rules for required fields, nulls, enums, formats and nested objects.

Workflow Why OpenAPI Examples Drift from Real API Responses

Debug documentation drift by comparing OpenAPI examples with live responses, generated clients, nullable fields and versioned API behavior.

Workflow Why API Retries Create Duplicate Requests

Debug duplicate API operations caused by client retries, proxy retries, timeout ambiguity and unsafe retry policies for writes.

Workflow How Idempotency Keys Prevent Double Submit Bugs

Use idempotency keys to protect checkout, form submission, imports and other write APIs from double-clicks, retries and timeout ambiguity.

Workflow How to Debug Webhook Replay and Duplicate Delivery

Debug webhook replay, duplicate delivery and out-of-order events by checking event ids, signatures, timestamps, retries and receiver idempotency.

Workflow Why GraphQL Errors Return 200 Status

Debug GraphQL responses that return HTTP 200 with an errors array, partial data, validation failures and resolver-level problems.

Workflow Why File Uploads Pass Extension Checks but Fail MIME Validation

Debug upload failures caused by mismatched file extensions, MIME types, content sniffing, browser FormData behavior and server validation rules.

Workflow Why Timezone Display Bugs Survive API Tests

Debug timezone display bugs that pass API tests but fail for users because of local rendering, DST, date-only values and browser locale settings.

Workflow Why JSON Number Precision Breaks Large IDs

Debug large numeric identifiers, cents, timestamps and database ids that change value when parsed as JavaScript numbers.

Workflow How to Redact Sensitive Data in API Logs

Build safer API debugging logs by redacting tokens, passwords, cookies, personal data and secrets while keeping useful request evidence.

Workflow Why API Version Headers Get Ignored

Debug API versioning failures caused by missing headers, proxy stripping, CORS exposure, generated clients and mixed URL/header version strategies.

Workflow Why Request Correlation IDs Disappear Between Services

Trace missing correlation ids across browsers, gateways, queues and microservices so API incidents can be followed end to end.

Workflow Why Streaming API Responses Break JSON Parsers

Debug Server-Sent Events, newline-delimited JSON and chunked responses that fail when client code expects one complete JSON document.

Workflow Why ETag Conflicts Cause 412 Precondition Failed

Debug optimistic concurrency failures where stale ETags, If-Match headers and cached resource versions cause rejected API updates.

Workflow Why Long API URLs Fail Before Reaching the Server

Debug URL length limits across browsers, proxies, CDNs and servers when large query strings fail before application code runs.

Workflow Why Locale Number Formatting Breaks API Payloads

Debug numbers that fail after UI formatting adds commas, decimal separators, currency symbols or non-breaking spaces before API submission.

Workflow Why Download Filenames Break with Non-ASCII Characters

Debug broken downloaded filenames caused by Content-Disposition encoding, browser differences, URL encoding and fallback filename handling.

Workflow Why API Deprecation Headers Get Missed

Debug missed API deprecation signals when clients ignore response headers, CORS exposure, sunset dates, docs and monitoring alerts.

Workflow How to Debug Background Job Status Polling

Debug async API workflows where job status polling stalls, repeats, returns stale state or loses correlation with the original request.

Workflow Why XML and SOAP Payloads Fail in Modern API Clients

Debug legacy XML and SOAP integrations that fail because of namespaces, envelopes, character encoding, content type and XML escaping.