Developer use-case guides
Short, practical guides for specific developer tasks. Each one shows a real example — sample input, expected output, and common mistakes — then links straight to the tool that does the job, all running locally in your browser.
Browse by topic cluster: JSON & API contract tools · Security & debugging tools · Data cleanup & QA tools.
JSON & API Contracts
RFC 6902: Why the remove target location must exist
Understand and fix the JSON Patch error where a remove operation target must exist. See RFC 6902 examples and test patches locally in your browser.
Open guide →JSON Pointer escaping: slash and tilde examples
Learn how to escape / and ~ in JSON Pointer paths using ~1 and ~0. Test JSON Pointer examples locally with JSON Patch & Pointer.
Open guide →JSON Patch vs JSON Merge Patch
Compare JSON Patch and JSON Merge Patch with examples. Understand operations, null handling, arrays and API PATCH request behavior.
Open guide →Generate JSON Patch from two JSON files
Generate JSON Patch operations by comparing two JSON documents. Create add, remove and replace operations locally in your browser.
Open guide →Apply JSON Patch online
Apply JSON Patch operations to a JSON document online. Test add, remove, replace, move, copy and test operations locally in your browser.
Open guide →Validate OpenAPI schema example JSON
Validate example JSON payloads against OpenAPI-style schemas. Check required fields, types, arrays and nested objects locally.
Open guide →Test JSONPath expressions against JSON
Test JSONPath expressions against a JSON document and see exactly which values they select. Build and debug filters locally.
Open guide →Diff two JSON API responses
Compare two JSON API responses to see exactly which fields were added, removed, or changed. Debug regressions locally.
Open guide →Inspect a JSON Schema
Read a JSON Schema at a glance — required fields, property types, and nested objects — without parsing the raw document.
Open guide →Analyze JSONL / NDJSON log lines
View newline-delimited JSON logs as a table and scan a field across many records without hand-parsing the stream.
Open guide →View all JSON and API contract tools →
Formatting & Conversion
Format JSON for API logs and debugging
Pretty-print and validate minified JSON from API logs so you can read it, find the syntax error, and debug faster.
Open guide →Format SQL for code review
Format messy one-line SQL into readable, consistently indented queries for pull requests and code review.
Open guide →Convert XML to JSON for API debugging
Convert SOAP or legacy XML responses to JSON so you can read, query, and diff them with modern tools.
Open guide →Convert JSON to YAML for Kubernetes
Convert JSON config into clean YAML for Kubernetes manifests and CI files, with correct indentation and types.
Open guide →Fix Base64 encoding and decoding errors
Fix common Base64 errors: bad padding, URL-safe vs standard alphabet, and UTF-8 mangling. Decode and re-encode correctly.
Open guide →Test a regex pattern online
Test a regular expression against sample text, see the matches and capture groups, and debug why it matches too much or nothing.
Open guide →Validate YAML syntax
Validate YAML and find the indentation, tab, and quoting errors that break CI and Kubernetes manifests.
Open guide →Cron & Dates
AWS EventBridge cron expression format
Understand AWS EventBridge cron expression format with six fields, examples, ? usage, weekday schedules and common mistakes.
Open guide →Cron expression: 6 fields vs 5 fields
Understand the difference between 5-field Unix cron and 6-field cron expressions used by Quartz, AWS and schedulers.
Open guide →Generate a cron expression
Build a cron expression from a plain-English schedule and preview the next run times for Linux, Quartz, or CI.
Open guide →Convert a time between time zones
Convert a time from one zone to another, accounting for daylight saving, for scheduling jobs, meetings, and incident timelines.
Open guide →Convert a Unix timestamp to a date
Convert a Unix epoch timestamp to a human-readable UTC and local date, and back, handling seconds vs milliseconds.
Open guide →API Clients / cURL
Convert cURL to Fetch
Convert cURL commands to JavaScript fetch code. Preserve method, headers, body and authorization details locally in your browser.
Open guide →Convert cURL to Axios
Convert cURL commands to Axios requests. Preserve HTTP method, URL, headers, JSON body and authorization details locally.
Open guide →Convert cURL to Python requests
Convert cURL commands to Python requests code with method, headers, JSON body and query parameters preserved.
Open guide →Parse HTTP headers
Parse a raw HTTP request or response into readable name/value pairs to debug caching, auth, and content-type issues.
Open guide →Inspect a SOAP XML response
Drill into a SOAP XML response with XPath to pull values out of the envelope, body, and namespaced elements.
Open guide →API Design & Testing
Debug API requests with a HAR capture
Load a HAR capture to inspect an API request and response — headers, body, status, and timing — side by side, locally.
Open guide →Analyze HTTP security headers
Check a response for HSTS, CSP, X-Content-Type-Options, and other security headers, and see which are missing or weak.
Open guide →Generate API request code snippets
Turn a method, URL, headers, and body into ready-to-run request snippets for curl, fetch, and more.
Open guide →Generate API client code from OpenAPI
Turn an OpenAPI operation into a ready-to-run client snippet — path, method, params, and body — in curl or fetch.
Open guide →Export OpenAPI to a Postman collection
Convert an OpenAPI spec into a Postman collection with folders, requests, and variables, so your team can start testing.
Open guide →Build a GraphQL request payload
Build the JSON body for a GraphQL HTTP request — query plus variables — and avoid the quoting and binding mistakes.
Open guide →URL Tools
Parse URL query parameters online
Parse a URL into protocol, host, path, query parameters, fragments and decoded values locally in your browser.
Open guide →Remove UTM parameters from a URL
Remove utm_source, utm_medium, utm_campaign and other tracking parameters from URLs while preserving useful query parameters.
Open guide →Decode URL query string online
Decode URL query strings and percent-encoded values such as %20, %2F and %3D locally in your browser.
Open guide →URL-encode query string values
Percent-encode query string values so spaces, ampersands, and slashes survive in a URL — and decode them back.
Open guide →Security / Debugging
Sanitize a HAR file before sharing it with support
Sanitize HAR files before sending them to vendors or support teams. Redact cookies, tokens, Authorization headers and API keys locally.
Open guide →Does a HAR file contain cookies and tokens?
Learn what sensitive data HAR files can contain, including cookies, Authorization headers, bearer tokens, API keys and request payloads.
Open guide →Verify Stripe webhook signature locally
Debug Stripe webhook signature verification issues. Check payload, timestamp, signing secret and HMAC signature locally.
Open guide →Verify GitHub webhook signature locally
Verify GitHub webhook signatures using the payload, secret and X-Hub-Signature-256 header. Debug HMAC SHA-256 mismatches locally.
Open guide →Decode a JWT token and inspect its claims
Decode a JWT to read its header and claims, check the expiry, and spot problems — without verifying or uploading the token.
Open guide →Decode an X.509 certificate
Decode an X.509 certificate to read its subject, issuer, validity dates, and SANs from PEM — locally, without uploading it.
Open guide →Redact PII before sharing logs
Find and redact emails, phone numbers, and other PII in logs before sharing them with vendors or pasting into a ticket.
Open guide →Find secrets and API keys in config files
Scan config and .env files for leaked API keys, tokens, and passwords before you commit or share them.
Open guide →Verify a JWT signature
Verify a JWT signature against a secret (HMAC) or public key (RSA/ECDSA) and check the claims and expiry — locally.
Open guide →View all security and debugging tools →
Data, Diff & Compare
Compare two CSV files by key
Compare two CSV files by ID, email, order number or another key. Find missing rows, changed values and duplicate keys locally.
Open guide →Find missing rows between two CSV files
Find rows that exist in one CSV file but not another using a key column such as ID, email, SKU or order number.
Open guide →Diff two text files
Compare two blocks of text or config line by line to see what was added, removed, or changed.
Open guide →Compare two email lists
Compare two email lists to find what is in both, only in one, or duplicated — case-insensitively.
Open guide →Inspect and clean a large CSV file
Open a large CSV in the browser to inspect columns, fix delimiters, and spot whitespace or encoding issues before importing.
Open guide →Compare two environment configs
Diff two environment configs (staging vs production) to find missing keys, changed values, and drift — by key.
Open guide →Clean and deduplicate a list of lines
Trim whitespace, drop blanks, remove duplicates, and sort a list of lines — for IDs, emails, or log lines.
Open guide →View all data cleanup and QA tools →
SQL & Tabular Data
Build SQL joins
Build INNER, LEFT, and multi-table SQL joins from your table and column names, with the right ON conditions.
Open guide →Generate a SQL IN clause from a list
Turn a list of IDs or values into a properly quoted SQL IN (...) clause, with chunking for long lists.
Open guide →Convert CSV to SQL INSERT statements
Turn CSV rows into SQL INSERT or upsert statements with the right column list and quoting.
Open guide →Convert JSON to CSV for Excel
Convert a JSON array of objects into CSV that opens cleanly in Excel, with flattened nested fields and a header row.
Open guide →DevOps & Config
Lint a Dockerfile before building
Catch best-practice issues — unpinned tags, missing USER, cache-busting layer order — before you build.
Open guide →Generate a Kubernetes Deployment YAML
Generate a valid Deployment manifest from image, replicas, ports, and labels — with the selector matching the template labels.
Open guide →Convert a .env file to JSON
Convert a .env file into JSON for config loaders and tooling, with quotes, comments, and types handled.
Open guide →Write a Docker Compose file
Build a docker-compose.yml from services, images, ports, and environment — with correct indentation and wiring.
Open guide →Encoding, Hashing & Generators
Encode and decode text online
Encode or decode text as Base64, URL percent-encoding, hex, or HTML entities — in one place, locally.
Open guide →Hash text online (SHA-256, MD5)
Compute a SHA-256, SHA-1, or MD5 hash of text to verify integrity or compare values.
Open guide →Convert a JWK / JWKS to PEM
Convert a JSON Web Key into a PEM public key for libraries that verify JWTs with PEM.
Open guide →Generate a secure password
Generate a strong random password with chosen length and character sets, using secure browser randomness.
Open guide →Generate a UUID (v4)
Generate a random version-4 UUID for IDs, keys, and test data — one at a time or in bulk.
Open guide →Generate lorem ipsum placeholder text
Generate placeholder text by paragraphs, sentences, or words to fill mockups and test layouts.
Open guide →Related
- All tools — the full utility catalog.
- Release checklists — browser-only validation gates.
- Workflows — chain tools into multi-step workflows.