Tool tutorials

Each tutorial solves one real problem with one of myfree browser tools: what to paste, what you get back, and what to watch out for.

• How to calculate tokens per minute
  Calculate how many requests fit in a minute from an RPM limit, a TPM limit, and the tokens in each request. You type every number.
  Tool: Token Rate Calculator
• How to check whether a version satisfies a semver range
  Test one version, or a list of versions, against an npm semver range. See the expanded range, including the -0 prerelease bound npm adds.
  Tool: Semver Range Calculator
• How to sort JSON object keys
  Sort the keys of a JSON object in the browser. Arrays stay in order. You can sort nested objects, and you can ignore letter case.
  Tool: JSON Key Sorter
• How to generate a random secret key
  Generate a random secret for an HMAC or an API token. Pick the byte length, then copy hex, Base64, or Base64url. The key stays in the browser.
  Tool: Secret Key Generator
• How to convert TOML to JSON
  Convert a TOML document to JSON in the browser, then turn that JSON back into TOML. Dates become strings. NaN and Infinity become null.
  Tool: TOML to JSON Converter
• How to parse a server-sent events body
  Split a finished text/event-stream body into events in the browser. Each event has a name, an id, and data. A block with no blank line is dropped.
  Tool: SSE Frame Parser
• How to create a Basic Auth header
  Build an HTTP Basic Authorization header from a user-id and password in the browser. UTF-8 mode uses NFC, then UTF-8, then Base64. Credentials stay off the URL.
  Tool: Basic Auth Header
• How to normalize a Unicode string to NFC
  Normalize a string to NFC in the browser and read the code points before and after. The page also shows NFD, NFKC, and NFKD. The string is not put in the URL.
  Tool: Unicode Normalization
• How to convert form urlencoded data to JSON
  Convert an application/x-www-form-urlencoded body to JSON in the browser, then back again. Repeated keys become arrays, and a plus sign becomes a space.
  Tool: URL-encoded Form to JSON
• How to calculate exponential backoff with jitter
  Set a base delay, a multiplier, and a cap, then read the wait before each retry. Compare no jitter with full, equal, and decorrelated jitter.
  Tool: Exponential Backoff Calculator
• How to calculate cosine similarity
  Paste two JSON arrays into the cosine similarity calculator. Read the cosine, the dot product, both magnitudes, and the Euclidean and Manhattan distances.
  Tool: Cosine Similarity Calculator
• How to convert OpenAPI to TypeScript
  Convert an OpenAPI 3.0 or 3.1 document into TypeScript interfaces in the browser, including schemas, parameters, and JSON request and response bodies.
  Tool: OpenAPI to TypeScript
• How to convert XML to JSON
  Convert an XML document to JSON in the browser, with attributes, repeated elements, and text mapped by one documented convention.
  Tool: XML to JSON Converter
• How to generate a Subresource Integrity hash
  Generate a Subresource Integrity hash in the browser for a script or stylesheet, then copy the integrity attribute and the tag.
  Tool: Subresource Integrity Generator
• How to fix invalid JSON from an LLM
  Fix invalid JSON from an LLM in the browser. Repair code fences, trailing commas, comments, single quotes, and cut-off brackets, then copy the valid JSON.
  Tool: JSON Repair
• How to compare two JSON objects
  Compare two JSON objects in the browser and see every added, removed, changed, or moved field by path. Key order and indentation are ignored.
  Tool: JSON Diff
• How to compare .env files
  Compare a .env file with .env.example in the browser. Find missing keys, extra keys, empty values, and repeated keys before you deploy.
  Tool: .env Diff
• How to convert a cURL command to JavaScript fetch
  Turn a cURL command from API docs into JavaScript fetch code with a free converter, then fix what curl does differently: content types, CORS and cookies.
  Tool: cURL to Code
• How to convert a docker run command to Docker Compose
  Turn a docker run command into a compose.yaml file with a free converter, then fix the parts that need you: named volumes, secrets, networks and limits.
  Tool: Docker Run to Compose Converter
• How to count tokens in a prompt
  Count the tokens in a prompt with a free browser tokenizer, see why the same text gives different counts, and count tokens in your own JavaScript code.
  Tool: LLM Tokenizer Visualizer