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 →View all JSON and API contract tools →
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 →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 →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 →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 →View all security and debugging tools →
CSV / Data Comparison
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 →View all data cleanup and QA tools →
Related
- All tools — the full utility catalog.
- Release checklists — browser-only validation gates.
- Workflows — chain tools into multi-step pipelines.