Sources matrix

Sources

Status: NORMATIVE (user responsibility advisory). This document lists every source doiget integrates with, the access prerequisites, and a pointer to each source's official Terms of Service. Users are responsible for ensuring they have the right to access content via these sources and for compliance with each source's ToS.

1. Source matrix

Source	Tier	Phase	Auth	ToS link	doiget feature
Crossref	1 (OA)	1	none	https://www.crossref.org/services/metadata-retrieval/rest-api/	always-on
Unpaywall	1 (OA)	1	email (polite pool)	https://unpaywall.org/products/api	always-on
arXiv	1 (OA)	1	none	https://info.arxiv.org/help/api/index.html	always-on
OpenAlex	2 (metadata)	4	none	https://docs.openalex.org/how-to-use-the-api/api-overview	`--features metadata` + `DOIGET_ENABLE_OPENALEX`
Semantic Scholar	2 (metadata)	4	API key (optional)	https://www.semanticscholar.org/product/api	`--features metadata` + `DOIGET_ENABLE_S2`
DOAJ	2 (metadata)	4	none	https://www.doaj.org/api	`--features metadata` + `DOIGET_ENABLE_DOAJ`
Springer Nature OA	3 (institutional)	5a	API key	https://dev.springernature.com/	`--features tdm-springer` + key + agree
APS Harvest TDM	3 (institutional)	5b	API key	https://harvest.aps.org/	`--features tdm-aps` + key + agree
Elsevier ScienceDirect TDM	3 (institutional)	5c	API key	https://www.elsevier.com/legal/tdmrep	`--features tdm-elsevier` + key + agree

2. User responsibility

For each source the user invokes, the user is the contracting party. doiget does not hold any credential for any user. Before enabling a source, ensure that you:

Have read and accepted the source's Terms of Service.
Hold the institutional or personal access rights the source requires.
Comply with the source's politeness policy (rate limit, attribution).
Are operating from a network and device authorized to use those rights.

doiget enforces a hard rate cap of 5 fetches per second per process to make polite behavior the default (LEGAL.md §6 safeguard 8).

3. Default release binaries

cargo install doiget (default) compiles Tier 1 only. Tier 2 metadata sources require an opt-in build:

cargo install doiget --features metadata

Tier 3 TDM sources are individually feature-flagged and require user-driven build:

cargo install doiget --features metadata,tdm-springer
cargo install doiget --features metadata,tdm-aps
cargo install doiget --features metadata,tdm-elsevier

There is no tdm-all umbrella feature (SCOPE.md §non-goal 12).

4. Source-specific notes

Crossref

Public, no-auth API. Polite pool requires User-Agent with contact email ([network] user_agent in config.toml).
doiget uses Crossref for: DOI → metadata; OA URL where Crossref's link array contains a free-to-read entry.

Unpaywall

Free, but the polite pool requires email=alice@example.org in the URL. Set [network] unpaywall_email in config.toml.
doiget uses Unpaywall for: OA URL discovery for a given DOI, with license metadata.

arXiv

Public, no-auth API, but the API has a 3-second-per-request rate guideline. doiget's global 5/sec cap respects this.
doiget uses arXiv for: arXiv id → PDF + metadata.

OpenAlex / Semantic Scholar / DOAJ

Metadata enrichment only. doiget does not fetch PDFs from these unless the response includes an OA URL whose host is on the per-source allowlist.

TDM sources

Each requires:

A Cargo feature compiled in (tdm-elsevier, tdm-aps, tdm-springer).
The user's API key in DOIGET_KEY_<PUBLISHER> env or [tdm.<publisher>] api_key in credentials.toml.
The agreement env DOIGET_AGREE_TDM_<PUBLISHER>=1.

If any of the three is missing, the source is unavailable at runtime (CAPABILITY.md §2).

5. Adding a new source

A new source addition requires:

A new GitHub Discussion describing the source, its access pattern, and Tier classification.
An ADR locking the Tier and (if Tier 3) the Cargo feature name.
An entry in this document with the official ToS link and prerequisites.
A doc in INTEGRATION/<source>.md if user-side configuration is non-trivial.
Update of this matrix.

6. Politeness defaults

doiget's defaults are designed to be on the polite side of every source we know of:

5 fetches per second, regardless of source.
Per-source backoff of 200 ms between consecutive requests.
User-Agent: doiget/<version> (+https://github.com/sotashimozono/doiget).
Honors Retry-After headers (treats 429 as RATE_LIMITED with the indicated wait).

If a source publishes a stricter rate guideline, doiget will adopt the stricter value at the per-source level rather than relax the global cap.

Source: site/content/developer/sources.md