Ipfs cid compute

ipfs-cid-compute · version 1.0.0 · Hashing & signatures · free, no key needed

Compute the CIDv0, CIDv1 dag-pb and CIDv1 raw content identifiers 'ipfs add' would give a single-chunk file.

Use when you need to: what cid would ipfs give this file · compute qm hash for ipfs · cidv1 for this content.

Decide before calling

Read the versioned contract and the supported scope below. Reuse ipfs-cid-compute@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 ipfs-cid-compute@1.0.0 for what cid would ipfs give this file. 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

• what cid would ipfs give this file
• compute qm hash for ipfs
• cidv1 for this content
• ipfs content address without running a node
• bafybe hash for this file
• predict the cid before pinning to ipfs

Not supported

• multi-chunk / multi-link dag-pb trees (this tool always represents content as one UnixFS chunk, kubo's default for anything at or under its size cap)
• pinning, adding or fetching content from an actual IPFS node

Behavior

• This tool always represents content as ONE UnixFS chunk (a single dag-pb node with no Links), exactly what kubo's default 256 KiB chunker produces for any input at or under this tool's max_content_bytes cap.
• cid_v1_raw: multihash = 0x12 0x20 || SHA-256(content) (content hashed directly, no UnixFS/dag-pb wrapper); CID = multibase('b') || varint(1) || varint(0x55 'raw') || multihash, base32-encoded (lowercase, unpadded).
• The UnixFS node bytes are: field 1 (Type=File) always present; field 2 (Data) present only when content is non-empty (an empty file omits the Data field entirely); field 3 (filesize) always present. The dag-pb node bytes are just field 1 (Data) = these UnixFS bytes, with no Links field.
• cid_v0_dag_pb: multihash = 0x12 0x20 || SHA-256(dag-pb node bytes); CID = base58btc(multihash) with no multibase prefix character and no version/codec varints.
• cid_v1_dag_pb: the same dag-pb node bytes and multihash as cid_v0_dag_pb, but wrapped as CIDv1 with codec 0x70 'dag-pb', base32-encoded.
• size is the decoded byte length of content.

Input

• content (string, required): max length 262144
• content_encoding (one of "utf8", "hex", "base64", "base64url", optional): default "utf8"

Output

• cid_v1_raw (string, required): pattern ^b[a-z2-7]+$
• cid_v0_dag_pb (string, required): pattern ^Qm[1-9A-HJ-NP-Za-km-z]+$
• cid_v1_dag_pb (string, required): pattern ^b[a-z2-7]+$
• size (integer, required): min 0

Limits

• max content bytes: 262144

Example

Request input:

{
  "content": ""
}

Response:

{
  "result": {
    "cid_v1_raw": "bafkreihdwdcefgh4dqkjv67uzcmw7ojee6xedzdetojuzjevtenxquvyku",
    "cid_v0_dag_pb": "QmbFMke1KXqnYyBBWxB74N4c5SBnJMVAiMNRcGu6x1AwQH",
    "cid_v1_dag_pb": "bafybeif7ztnhq65lumvvtr4ekcwd2ifwgm3awq4zfr3srh462rwyinlb4y",
    "size": 0
  }
}

How to call it

MCP

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

{
  "id": "ipfs-cid-compute",
  "version": "1.0.0",
  "input": {
    "content": ""
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/ipfs-cid-compute/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"content":""}'

The machine-readable contract is at /v1/tools/ipfs-cid-compute/versions/1.0.0.

CLI

node cli.mjs run ipfs-cid-compute 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

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