🌐 Crossref DOI Metadata QA

A per-DOI verdict product — not a metadata dump. Submit DOIs, get one deterministic QA verdict each: valid, not_found, or metadata_incomplete (with every missing required field named). Billed per definitive verdict.

Output is one doi_metadata_verdict row per result; billing is pay-per-event, the value event being one metadata qa check (a $0.02 start fee per run, then $0.05 per metadata qa check). Source: api.crossref.org.

No login, no API key and no CAPTCHA solving are involved: the source is read logged-out with an identified contact User-Agent.

📊 Sample Output

Real rows from run svzKET7yCydGgpBlD on build 0.1.4 (2026-09-17), the same input as the Quick start below — every value is as the source published it (emails masked, long text shortened):

doi	verdict	required_fields	present_fields	input	outcome
10.1038/nphys1170	valid	title,author,issued,type,container-title,publisher	title,author,issued,type,container-title,publisher	10.1038/nphys1170	answer
10.1145/3292500.3330701	valid	title,author,issued,type,container-title,publisher	title,author,issued,type,container-title,publisher	https://doi.org/10.1145/3292500.3330701	answer
10.9999/nonexistent-zzz-000	not_found	title,author,issued,type,container-title,publisher		10.9999/nonexistent-zzz-000	answer
	invalid_doi_syntax			not-a-doi	unparseable

The run finished with the status message: PARTIAL: 3 billable answer(s), 0 definitive non-billable (not-found/ambiguous), 0 unavailable, 1 unparseable of 4 | metadata-qa-check billable=3 | metadata-qa-check charged=3

✅ What you get

Each row is flat JSON with these fields (from the dataset schema and the sample run; a field the source does not publish for a given row is null):

• doi (string/null) — e.g. 10.1038/nphys1170
• verdict (string/null) — e.g. valid
• required_fields (string/null) — e.g. title,author,issued,type,container-title,publisher
• missing_fields (string/null) — null in every sample row
• present_fields (string/null) — e.g. title,author,issued,type,container-title,publisher
• title (string/null) — e.g. Measured measurement
• type (string/null) — e.g. journal-article
• publisher (string/null) — e.g. Springer Science and Business Media LLC
• record_type (string) — e.g. doi_metadata_verdict
• input (string/null) — e.g. 10.1038/nphys1170
• source (string/null) — e.g. https://api.crossref.org/works
• outcome (string/null) — e.g. answer
• outcome_reason (string/null) — e.g. DOI is not registered in Crossref

⚙️ Sample inputs

1. Quick start — the Store example (this is what the sample above came from)

{
  "dois": [
    "10.1038/nphys1170",
    "https://doi.org/10.1145/3292500.3330701",
    "10.9999/nonexistent-zzz-000",
    "not-a-doi"
  ],
  "requiredFields": [
    "title",
    "author",
    "issued",
    "type",
    "container-title",
    "publisher"
  ]
}

The sample run charged exactly: 1 × $0.02 apify-actor-start + 3 × $0.05 metadata-qa-check = $0.17 on the Free tier — every delivered row was billed.

2. A smaller, narrowed run

{
  "dois": [
    "10.1038/nphys1170",
    "https://doi.org/10.1145/3292500.3330701",
    "10.9999/nonexistent-zzz-000",
    "not-a-doi"
  ],
  "requiredFields": [
    "title",
    "author",
    "issued",
    "type",
    "container-title",
    "publisher"
  ]
}

A bounded run for checking the field shape before scheduling.

3. A full-size run

{
  "dois": [
    "10.1038/nphys1170",
    "https://doi.org/10.1145/3292500.3330701",
    "10.9999/nonexistent-zzz-000",
    "not-a-doi"
  ],
  "requiredFields": [
    "title",
    "author",
    "issued",
    "type",
    "container-title",
    "publisher"
  ]
}

The same input run on a schedule; each run is billed only for what it delivers.

🧾 JSON sample record

One real record from run svzKET7yCydGgpBlD, exactly as it lands in the dataset (emails masked, long text shortened):

{
  "doi": "10.1038/nphys1170",
  "verdict": "valid",
  "required_fields": "title,author,issued,type,container-title,publisher",
  "missing_fields": null,
  "present_fields": "title,author,issued,type,container-title,publisher",
  "title": "Measured measurement",
  "type": "journal-article",
  "publisher": "Springer Science and Business Media LLC",
  "record_type": "doi_metadata_verdict",
  "input": "10.1038/nphys1170",
  "source": "https://api.crossref.org/works",
  "outcome": "answer",
  "outcome_reason": null
}

🔧 How it works

Transport. Plain HTTPS from the Apify platform, no proxy. Every request carries an identified contact User-Agent.

Charging. Each metadata qa check is charged at the moment it is pushed (metadata-qa-check); a row that fails to charge is not delivered, so the dataset count always equals the charged count.

How it behaves

Each DOI is canonicalized (https://doi.org/…, doi: prefixes stripped) and syntax-validated. A syntactically valid DOI is looked up once against the official keyless Crossref REST API (contact-bearing UA, polite rate limit, bounded retries). The buyer-selected required-field profile (requiredFields, default: title, author, issued, type, container-title, publisher) is tested against the record:

• all present → valid;
• some missing → metadata_incomplete, with the missing fields named;
• DOI not registered in Crossref → not_found.

Input order is preserved. The verdict record carries minimal identifying context only (title, type, publisher) — the payload is the verdict, never a metadata dump.

Billing

Event	FREE	BRONZE	SILVER	GOLD+
apify-actor-start (one-time actor start)	$0.02	$0.02	$0.02	$0.02
metadata-qa-check (per definitive verdict)	$0.05	$0.045	$0.04	$0.0335

A definitive verdict (valid / not_found / metadata_incomplete) is charged once. Locally-invalid DOI syntax and Crossref outages are emitted but never charged. Start fee $0.02.

Differentiation

• vs our crossref-citation-mcp: this is batch QA verdicts for metadata operations, not per-call retrieval for agents.
• vs the store comparators: deterministic, order-preserving verdicts with named missing fields, not search exports.

Source

https://api.crossref.org/works

What is not done. No login, no cookie or CAPTCHA bypass, no private or personal-account data, no browser automation.

💰 Pricing example

Event	Free	Bronze	Silver	Gold
Actor Start (apify-actor-start)	$0.02	$0.02	$0.02	$0.02
Metadata QA Check (metadata-qa-check)	$0.05	$0.04	$0.04	$0.03

Worked at the live Free-tier price:

• 4 metadata qa checks: $0.02 start + 4 × $0.05 = $0.22
• 25 metadata qa checks: $0.02 start + 25 × $0.05 = $1.27
• 100 metadata qa checks: $0.02 start + 100 × $0.05 = $5.02

A run that delivers zero rows charges the $0.02 start fee only. A BLOCKED run (source refused) fails loud and charges no value event. The start fee is charged once per GB of run memory; the default run memory is 1024 MB.

Yield on the sample run: PARTIAL: 3 billable answer(s), 0 definitive non-billable (not-found/ambiguous), 0 unavailable, 1 unparseable of 4 | metadata-qa-check billable=3 | metadata-qa-check charged=3.

⚖️ Legal & ToS

This actor reads public, logged-out pages and feeds published by api.crossref.org. It collects only what the source publishes to any visitor, identifies itself with a contact User-Agent, and does not access accounts, private data or anything behind authentication. Use the output in line with the source's terms and your local law; the intended use is B2B research and monitoring.

❓ FAQ

Q: Do I need an API key or a login?
A: No. The source (api.crossref.org) is read logged-out; the input schema has no key field and the actor carries no secrets.

Q: Why did my run return 0 rows?
A: Read the run's status message. GENUINE_EMPTY means the source was read and had nothing in scope for your input; BLOCKED means the source refused and the run failed without billing a value event — retry later or narrow the input. A zero-row run bills the start fee only.

Q: How fresh is the data?
A: Every run reads the source live at run time; nothing is cached between runs. Put it on a schedule for a continuous feed.

Q: What formats can I export?
A: The dataset downloads as JSON, CSV, Excel, XML or RSS from the run's Dataset tab or the Apify API, and any run can push to a webhook or integration.

Q: How is this different from the other web QA and enrichment tools actors?
A: Same output shape and billing model; this one covers api.crossref.org. The siblings under Related Actors cover the other sources or slices — run several on one schedule for a combined feed.

Q: Are there rate limits?
A: The actor paces itself against the source; there is no per-buyer limit beyond your Apify plan's concurrency.

🆘 Troubleshooting

• Run FAILED with BLOCKED → the source refused the request or changed its page shape → nothing was billed beyond the start fee; retry after a while, and if it persists open an Issue with the run id.
• Fewer rows than expected → the source had fewer items in scope → widen the input.
• Input validation error on start → a field is outside the schema's allowed values → start from the Quick start block and change one field at a time.
• Run TIMED-OUT → a very wide request on a slow day → raise the run timeout in Run options or narrow the input; what was delivered before the timeout is still in the dataset.

🔗 Related Actors

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• 🏢 About NexGenData — NexGen Watch is NexGenData's fleet of 256 public monitoring and lookup actors built on official sources, pay-per-result. Browse the catalog at apify.com/nexgenwatch.

⭐ Found this useful?

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