# CRC-32

`crc32` · version 1.0.0 · Encoding & checksums · free, no key needed

CRC-32 of UTF-8 bytes (ISO 3309 / ZIP / PNG polynomial). Integrity check only; no security claim.

**Use when you need to: crc32 · crc-32 · zip crc32.**

## Supported

- crc32
- crc-32
- zip crc32

## Not supported

- crc32c
- hmac
- sha
- cryptographic hash

## Behavior

- UTF-8 encode text. CRC-32 with polynomial 0xEDB88320, init 0xFFFFFFFF, final XOR 0xFFFFFFFF.
- hex is 8 lowercase hex digits, zero-padded. value is the unsigned 32-bit integer as a JSON number (0..4294967295).
- This is an integrity checksum, not a cryptographic hash, MAC, or password hash.

## Input

- `text` (string, required): max length 256000

## Output

- `hex` (string, required): min length 8; max length 8
- `value` (integer, required): min 0; max 4294967295

## Limits

- max input bytes: 256000

## Example

Request input:

```json
{
  "text": ""
}
```

Response:

```json
{
  "result": {
    "hex": "00000000",
    "value": 0
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "crc32",
  "version": "1.0.0",
  "input": {
    "text": ""
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/crc32/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"text":""}'
```

The machine-readable contract is at [/v1/tools/crc32/versions/1.0.0](/v1/tools/crc32/versions/1.0.0).

### CLI

```sh
node cli.mjs run crc32 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

## Related tools

- [Adler-32](/tools/adler32): Adler-32 of UTF-8 bytes (RFC 1950). Integrity check only; no security claim.
- [Base64 UTF-8](/tools/base64-utf8): Decode standard Base64 to UTF-8 text. Transformation only; no security claim.
- [Hex bytes concat](/tools/hex-bytes-concat): Concatenate a bounded ordered list of lowercase hex byte strings into one hex string.
- [Hex bytes slice](/tools/hex-bytes-slice): Slice a lowercase hex byte string by explicit byte-index bounds, half-open like Array.slice.
- [Hex bytes xor](/tools/hex-bytes-xor): Byte-wise XOR of two equal-length lowercase hex byte strings. Transformation only; no cryptographic security claim.
- [UTF-8 Base64](/tools/utf8-base64): Encode a Unicode string as standard Base64 of its UTF-8 bytes. Transformation only; no security claim.