Utility APIs for developers

20 text, encoding, checksum, number and identifier APIs. Real requests, complete parameters and tested examples.

Quick start

Send a JSON object with POST. No API key is required. Successful responses contain ok:true and data; API-generated errors contain ok:false and error. Start with an endpoint below or download the OpenAPI 3.1 definition.

curl --fail-with-body --request POST 'https://www.base64.sh/api/v1/base64/' \
  --user-agent 'Base64.sh API example/1.0' --header 'Content-Type: application/json' \
  --data-raw '{"text":"Hello 世界"}'

Encoding

Base64 API

Encode UTF-8 text as Base64 or decode it through a JSON HTTP API, with standard and URL-safe alphabets.

Base32 API

Convert UTF-8 text to RFC 4648 Base32 and decode valid Base32 text with a scriptable HTTP endpoint.

Base58 API

Encode and decode short UTF-8 strings using the Bitcoin Base58 alphabet, preserving leading zero bytes.

URL Encoding API

Percent-encode or decode a URL component, full URI or form value with explicit encoding modes.

Hex to Text API

Decode hexadecimal UTF-8 bytes into text or encode text as hexadecimal, with strict byte validation.

Text to Binary API

Convert UTF-8 text into eight-bit binary bytes, or decode a binary byte string into text.

HTML Entity API

Encode plain text as HTML entities or decode named and numeric HTML character references through an API.

ROT13 and ROT47 API

Apply ROT13 to ASCII letters or ROT47 to printable ASCII characters through a reversible text API.

Data

JSON Formatter API

Format, minify or validate JSON without rounding large numbers or losing duplicate and prototype-like keys.

Checksums

SHA-1 API

Calculate a SHA-1 digest of UTF-8 text and receive its lowercase hexadecimal representation in JSON.

SHA-256 API

Calculate a SHA-256 digest of UTF-8 text and receive its lowercase hexadecimal representation in JSON.

SHA-512 API

Calculate a SHA-512 digest of UTF-8 text and receive its lowercase hexadecimal representation in JSON.

CRC32 API

Calculate the standard IEEE CRC-32 checksum of UTF-8 text, returning hexadecimal and unsigned decimal values.

Text

Word Counter API

Count words, Unicode characters, sentences, paragraphs and UTF-8 bytes, with configurable reading and speaking time estimates.

Slug Generator API

Generate URL slugs with accent transliteration, configurable separators, word-boundary length limits and optional stop-word removal.

Text Line Tools API

Sort, deduplicate, reverse, trim, number or wrap text lines through a single JSON endpoint.

Simplified and Traditional Chinese API

Convert Chinese text with OpenCC phrase dictionaries, including mainland, Taiwan and Hong Kong variants.

Identifiers

UUID v4 API

Generate one or up to 100 cryptographically random UUID version 4 identifiers per API request.

Numbers

Number to Words API

Spell signed decimal numbers in English while preserving long integer strings and each fractional digit.

RMB Uppercase API

Convert decimal amounts into Chinese uppercase RMB wording with simplified or traditional financial characters.

Limits and error handling

Requests require Content-Type: application/json and a UTF-8 JSON object. The body limit is 32 KiB (32,768 bytes), text fields allow up to 16,384 Unicode code points unless a smaller limit is listed, and responses are limited to 256 KiB. Unknown parameters and unpaired Unicode surrogates in parameter strings are rejected. Send inputs in the request body, not query parameters.

Anonymous access is limited to approximately 60 POST requests per minute per IP address, shared across endpoints in each Cloudflare location. Shared networks share the allowance. Counters are eventually consistent, not a guaranteed global quota. On HTTP 429, wait for the Retry-After interval before retrying; avoid immediate retry loops.

Programmatic clients should send an identifying User-Agent, as shown in the cURL and Python examples. Browser fetch supplies its own header. Cloudflare may reject a generic or missing agent before the API runs; an edge-generated 403 can be plain text or HTML rather than the JSON envelope. See Cloudflare error 1010.

400 · Invalid input: Malformed JSON, missing fields, unsupported options or invalid encoded text. Correct the input before retrying.
403 · Edge request blocked: Check the User-Agent and the Cloudflare error response before retrying.
404 · Unknown endpoint: Use a documented /api/v1/{tool}/ endpoint.
405 · Method not allowed: Use POST. OPTIONS is supported for browser CORS requests.
413 · Size limit exceeded: Reduce the request size or the generated output.
415 · Unsupported media type: Set Content-Type: application/json.
429 · Rate limited: Wait at least the Retry-After number of seconds.
500 / 503 · Service unavailable: Retry later with bounded backoff. Availability is not guaranteed.

API data processing

API inputs are sent over HTTPS and processed in memory by a Cloudflare Worker. The application does not persist submitted text or deliberately log request bodies, and API responses use Cache-Control: no-store. Cloudflare may process network metadata under its own policies. For local processing, use the corresponding browser tool. See the privacy policy.