arXiv API

arXiv is a preprint server for physics, mathematics, computer science, quantitative biology, quantitative finance, statistics, electrical engineering, and economics.

Important: The arXiv API returns Atom XML, not JSON. There is no JSON option.

Base URL

https://export.arxiv.org/api/query

Authentication

None required. Fully public.

Query Parameters

GET https://export.arxiv.org/api/query?search_query={query}&start={n}&max_results={n}

*At least one of search_query or id_list must be provided. They can be combined (intersection).

Search Field Prefixes

Boolean Operators

• AND -- both conditions
• OR -- either condition
• ANDNOT -- exclude
• Parentheses for grouping (URL-encode as %28 / %29)
• Quoted phrases (URL-encode as %22)

Example Queries

Search all fields:

https://export.arxiv.org/api/query?search_query=all:transformer+attention&max_results=5

Author + category:

https://export.arxiv.org/api/query?search_query=au:hinton+AND+cat:cs.LG&max_results=10

Title search:

https://export.arxiv.org/api/query?search_query=ti:%22attention+is+all+you+need%22

By ID:

https://export.arxiv.org/api/query?id_list=2103.15348

Multiple IDs:

https://export.arxiv.org/api/query?id_list=2103.15348,2005.14165,1706.03762

Date range -- the brackets must be percent-encoded as %5B / %5D:

https://export.arxiv.org/api/query?search_query=cat:cs.AI+AND+submittedDate:%5B202401010000+TO+202412312359%5D

Passing literal [ and ] to curl fails before the request is even sent: curl reads them as a globbing range and exits 3 (bad range specification) with no output and no HTTP status to diagnose. Verified 2026-07-27:

# exit 3, nothing fetched, no error body to read
curl -s "https://export.arxiv.org/api/query?search_query=submittedDate:[202401010000+TO+202401020000]"

# exit 0, totalResults 35 -- either fix works
curl -s  "https://export.arxiv.org/api/query?search_query=cat:cs.AI+AND+submittedDate:%5B202401010000+TO+202401020000%5D"
curl -sg "https://export.arxiv.org/api/query?search_query=cat:cs.AI+AND+submittedDate:[202401010000+TO+202401020000]"

Prefer the encoded form over curl -g: it is what the API expects, and it survives being copied into a fetch tool, a Python client, or a shell that is not curl. Timestamps are YYYYMMDDHHMM in UTC and the range is inclusive on both ends.

Response Format (Atom XML)

<feed xmlns="http://www.w3.org/2005/Atom">
  <opensearch:totalResults>1234</opensearch:totalResults>
  <opensearch:startIndex>0</opensearch:startIndex>
  <opensearch:itemsPerPage>10</opensearch:itemsPerPage>

  <entry>
    <id>http://arxiv.org/abs/1706.03762v7</id>   <!-- http, while the links below are https -->
    <title>Attention Is All You Need</title>
    <summary>The dominant sequence transduction models are based on...</summary>
    <published>2017-06-12T17:57:34Z</published>
    <updated>2023-08-02T00:00:12Z</updated>
    <author><name>Ashish Vaswani</name></author>
    <author><name>Noam Shazeer</name></author>
    <!-- more authors -->
    <category term="cs.CL" scheme="http://arxiv.org/schemas/atom"/>
    <arxiv:primary_category term="cs.CL"/>
    <link rel="alternate" type="text/html" href="https://arxiv.org/abs/1706.03762v7"/>
    <link rel="related" type="application/pdf" title="pdf" href="https://arxiv.org/pdf/1706.03762v7"/>
    <arxiv:comment>15 pages, 5 figures</arxiv:comment>
    <!-- <arxiv:doi> and <arxiv:journal_ref> appear only when the author registered them.
         1706.03762 has neither. -->
  </entry>
</feed>

Key XML elements per entry

<arxiv:doi> is not the arXiv DOI

<arxiv:doi> carries the DOI of the published journal version (10.1103/PhysRevD.50.43), and it is absent for any preprint that was never published or whose author never registered it. Verified 2026-07-27: id_list=1706.03762 ("Attention Is All You Need") returns no <arxiv:doi> element at all.

arXiv also mints its own DOI, conventionally 10.48550/arXiv.{id}, but the API never returns it, and constructing one is only sometimes a usable key. Verified 2026-07-27 for 1706.03762:

The OpenAlex miss is not a case problem -- doi:10.48550/arxiv.2102.05095 and doi:10.48550/arXiv.2102.05095 both return 200, so the lookup is case-insensitive and does work for many arXiv preprints. It is that **not every arXiv paper is under a 10.48550 DOI there**: OpenAlex holds "Attention Is All You Need" as W2626778328 with DOI 10.65215/2q58a426, a prefix arXiv now also uses.

So do not treat a constructed arXiv DOI as an identifier that works everywhere, and do not report a 404 from it as "paper not found". Cross-reference by the arXiv ID instead -- Semantic Scholar's ARXIV:{id} prefix (see references/semantic-scholar.md) -- or by title search, and fall back to a constructed DOI only after that fails.

Parsing Tips

Use scripts/arxiv_atom.py rather than re-deriving the parse:

curl -s "https://export.arxiv.org/api/query?id_list=1706.03762" | python3 scripts/arxiv_atom.py -

It emits one JSON record per entry (arxiv_id, version, title, abstract, authors, categories, doi, pdf_url, dates) plus the feed's total_results, with the namespaces and the traps below already handled.

If you do parse it yourself: the namespace is http://www.w3.org/2005/Atom, with arXiv extensions in http://arxiv.org/schemas/atom. Four things bite:

• **The feed has its own <link>.** Before the first <entry> there is a <link type="application/atom+xml"> pointing back at the query. Selecting "the first <link>" yields the query URL, not a paper. Match on rel/type: the abstract page is rel="alternate" type="text/html", the PDF is rel="related" type="application/pdf" title="pdf".
• The URL schemes are inconsistent within a single response. Verified 2026-07-27 on id_list=1706.03762: the entry's <id> is http://arxiv.org/abs/1706.03762v7, while the <link href> values for the same pages are https://arxiv.org/abs/... and https://arxiv.org/pdf/..., and the feed-level <id> is https://arxiv.org/api/.... Never string-match on the scheme. Take the complete path after /abs/; legacy IDs such as hep-th/9901001v1 contain a slash.
• The ID carries a version suffix. 1706.03762v7, not 1706.03762. Strip the trailing vN before comparing against a DOI, a Semantic Scholar ARXIV: lookup, or a user-supplied ID.
• **<title> and <summary> arrive hard-wrapped**, with newlines and runs of spaces mid-sentence. Collapse whitespace before display or comparison.

Failure Modes

None of these are HTTP errors. All verified 2026-07-27.

**An unknown field prefix is silently rewritten to all:.** search_query=badfield:xyz does not fail -- arXiv reinterprets it and runs all:badfield:xyz, returning plausible hits for a query you did not ask for. The feed's own <title> echoes the query as executed:

<title>arXiv Query: search_query=all:badfield:xyz&amp;id_list=&amp;start=0&amp;max_results=1</title>

So a typo in a prefix (author: instead of au:, abstract: instead of abs:) degrades a targeted search into a full-text one with no warning. Use only the prefixes in the table above, and check the feed <title> against the query you sent before trusting the results.

A malformed parameter returns an error dressed as a result. start=notanumber returns HTTP 200, <opensearch:totalResults>1</opensearch:totalResults>, and one <entry>:

<entry><title>Error</title><summary>start must be an integer</summary></entry>

An agent that reads totalResults as 1 and takes entry[0] reports a paper titled "Error". Check for <title>Error</title> before treating any entry as a paper. (Omitting both search_query and id_list does return HTTP 400, with the same Error entry.)

Throttling is not XML. Exceed the rate limit and arXiv replies with the bare plain-text body Rate exceeded. -- 14 bytes, no feed, no Atom envelope. It arrives with HTTP 429, and under sustained throttling the connection is dropped outright (curl reports HTTP=000). Since curl -s without -f prints the body whatever the status, a pipeline that goes straight to a parser sees a syntax error at line 1 column 0, which reads like a corrupt response rather than a pacing problem. Check the status and the raw bytes before concluding the API is broken; the fix is to wait, not to retry harder.

This is easy to trigger -- the limit is one request per three seconds -- and malformed requests are penalized harder than valid ones: observed 2026-07-27, valid queries were being served normally while a repeated start=notanumber request stayed throttled for over 30 minutes. Do not retry a request that arXiv rejected; fix it first.

A genuine no-match is quiet and correct: totalResults 0 and zero <entry> elements. An unknown arXiv ID in id_list behaves the same way -- id_list=9999.99999 gives totalResults 0, no entry, no error. Report that as "not found in arXiv", not as a failed request.

scripts/arxiv_atom.py exits non-zero on the Error entry and reports the echoed query, so a rewritten prefix surfaces instead of passing silently.

Common Categories

Full list: https://arxiv.org/category_taxonomy

Rate Limits

• At least 3 seconds between requests, per the API usage guidance
• Single connection at a time
• Search results are cached daily -- same query won't show new results within 24 hours
• For bulk data, use the OAI-PMH interface instead

Official sources reviewed 2026-09-30

• https://info.arxiv.org/help/api/user-manual.html
• https://info.arxiv.org/help/api/tou.html