# Doi parse

`doi-parse` · version 1.0.0 · Identifiers & check digits · free, no key needed

Parse a DOI (bare, doi: or doi.org URL) into prefix, suffix, directory indicator, registrant code and canonical forms.

**Use when you need to: parse a doi · extract doi prefix and suffix · convert a doi to a doi.org link.**

## Decide before calling

Read the [versioned contract](/v1/tools/doi-parse/versions/1.0.0) and the supported scope below. Reuse `doi-parse@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 `doi-parse@1.0.0` for parse a doi. 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

- parse a doi
- extract doi prefix and suffix
- convert a doi to a doi.org link
- normalize a doi url
- get the registrant code from a doi
- strip the doi colon prefix
- turn this doi into a clickable link

## Not supported

- resolving a DOI to the resource it names (no network access)
- validating that a DOI is actually registered
- a suffix containing a raw percent-encoded byte, whitespace or a non-ASCII character (see semantics; unsupported_input)

## Behavior

- Wrapper stripping: if doi starts with one of 'doi:', 'https://doi.org/', 'http://doi.org/', 'https://dx.doi.org/', 'http://dx.doi.org/' (matched case-insensitively, checked in that order), that wrapper alone is removed; at most one wrapper is stripped, and an unmatched string is used as-is.
- After stripping, the remainder must match 10.<digits>(.<digits>)*/<suffix>: literal directory indicator 10, a dot, one or more digit-only registrant-code groups separated by single dots, a single slash, then a non-empty suffix. The first slash after the registrant code is the boundary; everything after it, including further slashes, belongs to suffix. Anything else throws invalid_input.
- suffix characters are restricted to ASCII unreserved URI characters (A-Z a-z 0-9 - . _ ~), '/', and ( ) + , ; = @ ! * ' $ :. A suffix with any other character (including non-ASCII, '%' or whitespace) is well-formed DOI syntax but outside this tool's declared charset, so it throws unsupported_input.
- prefix is '10.' + the registrant-code groups; directory_indicator is the literal '10'; registrant_code is prefix with the leading '10.' removed (it may itself contain dots for sub-registrant groups).
- normalized_lowercase is prefix + '/' + suffix with a simple ASCII-only A-Z -> a-z mapping applied to the whole string; every other character, including non-ASCII, is left unchanged.
- uri is 'https://doi.org/' + prefix + '/' + suffix, in the original case (never lowercased).

## Input

- `doi` (string, required): min length 1; max length 200

## Output

- `prefix` (string, required)
- `suffix` (string, required)
- `directory_indicator` (constant "10", required)
- `registrant_code` (string, required)
- `normalized_lowercase` (string, required)
- `uri` (string, required)

## Limits

- max doi bytes: 200

## Example

Request input:

```json
{
  "doi": "10.1000/182"
}
```

Response:

```json
{
  "result": {
    "prefix": "10.1000",
    "suffix": "182",
    "directory_indicator": "10",
    "registrant_code": "1000",
    "normalized_lowercase": "10.1000/182",
    "uri": "https://doi.org/10.1000/182"
  }
}
```

## How to call it

### MCP

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

```json
{
  "id": "doi-parse",
  "version": "1.0.0",
  "input": {
    "doi": "10.1000/182"
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/doi-parse/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"doi":"10.1000/182"}'
```

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

### CLI

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

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

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