Hex bytes slice

hex-bytes-slice · version 1.0.0 · Encoding & checksums · free, no key needed

Slice a lowercase hex byte string by explicit byte-index bounds, half-open like Array.slice.

Use when you need to: hex bytes slice · slice hex byte string · byte-range slice of hex.

Decide before calling

Read the versioned contract and the supported scope below. Reuse hex-bytes-slice@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use hex-bytes-slice@1.0.0 for hex bytes slice. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

• hex bytes slice
• slice hex byte string
• byte-range slice of hex

Not supported

• negative indexes
• python wrap-around slicing
• uppercase hex
• 0x prefix
• code-point or character slicing
• decode hex to text

Behavior

• hex is a lowercase hex byte string: 0-9 and a-f only, two hex digits per byte, no 0x prefix, no separators, no whitespace, no uppercase.
• hex is bounded to 128000 bytes (256000 hex characters).
• start and end are JSON integers with Number.isInteger, each between 0 and the byte-count bound, counting whole bytes (not hex characters).
• The slice is the half-open byte interval [start, end): the byte at index end is not included.
• end must be greater than or equal to start; start and end must each be at most the byte length of hex. Negative indexes, wrap-around, and end < start are rejected rather than reinterpreted.
• A slice where start equals end is allowed at any valid position and returns an empty result.

Input

• hex (string, required): max length 256000
• start (integer, required): min 0; max 128000
• end (integer, required): min 0; max 128000

Output

• hex (string, required)

Limits

• max input bytes: 128000
• max index: 128000

Example

Request input:

{
  "hex": "aabbccdd",
  "start": 1,
  "end": 3
}

Response:

{
  "result": {
    "hex": "bbcc"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "hex-bytes-slice",
  "version": "1.0.0",
  "input": {
    "hex": "aabbccdd",
    "start": 1,
    "end": 3
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/hex-bytes-slice/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"hex":"aabbccdd","start":1,"end":3}'

The machine-readable contract is at /v1/tools/hex-bytes-slice/versions/1.0.0.

CLI

node cli.mjs run hex-bytes-slice 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Hex bytes xor: Byte-wise XOR of two equal-length lowercase hex byte strings. Transformation only; no cryptographic security claim.
• Hex bytes concat: Concatenate a bounded ordered list of lowercase hex byte strings into one hex string.
• Bech32 validate: Check Bech32 or Bech32m text and return a reason, without throwing when the checksum fails.
• Iso8859 semantic decode: Decode ISO-8859-6 Arabic, ISO-8859-8 Hebrew, or ISO-8859-11 Thai bytes into logical Unicode text.
• Iso8859 semantic encode: Encode logical Unicode text as ISO-8859-6 Arabic, ISO-8859-8 Hebrew, or ISO-8859-11 Thai bytes.
• Pem envelope format: Format a label and lowercase hex bytes as a canonical RFC 7468 PEM envelope.