# bioRxiv API: Search preprints

> Finds bioRxiv and medRxiv preprints whose title, abstract or subject matches all topic words, within a posting date range, newest first. Adds published journal details when available.

Unofficial. Not affiliated with or endorsed by bioRxiv.

- Page: https://fous.com/methods/biorxiv.org/search-preprints
- Method: `biorxiv.org/search_preprints`, version 1
- Website: biorxiv.org
- Returns: title, authors, posting date, server, subject, abstract, PDF and preprint links, journal and DOI
- Effect: read (it gets data and changes nothing)
- Sign-in: none needed
- Cost: 1 credit per completed run (1¢ with pay as you go); failed runs are free
- Verified: Nov 2, 2026

## Inputs

| Field | Type | Required | In the run below | Description |
|---|---|---|---|---|
| `query` | string | yes | `"breast cancer"` | Topic words to find in preprint titles, abstracts, and subject categories, for example gut microbiome depression. |
| `server` | string | no | `"medrxiv"` | Preprint server to search: both, biorxiv or medrxiv. One of "both", "biorxiv", "medrxiv". Default "both". |
| `end_date` | string | no | `"2026-09-28"` | Last posting date, inclusive, as YYYY-MM-DD, for example 2026-09-29. Defaults to today. |
| `start_date` | string | no | `"2026-09-27"` | First posting date, inclusive, as YYYY-MM-DD, for example 2026-09-01. Defaults to 30 days before today. |
| `max_results` | integer | no | `5` | Maximum number of matching preprints, for example 20. Default 20. |

## Output

From a run on Oct 23, 2026, shortened. Its input:

```json
{
  "query": "breast cancer",
  "server": "medrxiv",
  "end_date": "2026-09-28",
  "start_date": "2026-09-27",
  "max_results": 5
}
```

Its output:

```json
{
  "preprints": [
    {
      "doi": "10.64898/2026.09.25.26364003",
      "title": "Pixel-Level Quantification of Subcutaneous Shear-Wave Velocity Heterogeneity for Grading Lymphatic Obstruction in Breast Cancer-Related Lymphedema",
      "server": "medRxiv",
      "authors": "Hoe, Z. Y.; Chou, C.-P.; Tzeng, Y.-D.; Ding, R.-S.; Pan, C.-T.; Lee, M.-C.; Lee, C.-H.",
      "journal": null,
      "abstract": "ObjectivesTo develop and validate pixel data analysis (PDA) for reconstructing pixel-level shear-wave velocity (SWV) from saved Holder-Optimized Elastography (HOE) elastograms and to determine whether whole-field subcutaneous heterogeneity provides a quantitative signature of lymphatic obstruction c…",
      "pdf_link": "https://www.medrxiv.org/content/10.64898/2026.09.25.26364003v1.full.pdf",
      "date_posted": "2026-09-28",
      "journal_link": null,
      "preprint_link": "https://www.medrxiv.org/content/10.64898/2026.09.25.26364003v1",
      "subject_category": "radiology and imaging"
    },
    {
      "doi": "10.64898/2026.09.08.26362522",
      "title": "Epigenetic misprogramming of cell differentiation links transient viral infection to chronic diseases across tissues",
      "server": "medRxiv",
      "authors": "Friedenson, B.",
      "journal": null,
      "abstract": "Virus-induced epigenetic changes in stem-cell differentiation pathways emerge here as a shared mechanism linking fundamentally different chronic diseases, offering candidate biomarkers and new intervention targets. Chronic diseases increasingly trace back to transient viral exposure, yet unrelated p…",
      "pdf_link": "https://www.medrxiv.org/content/10.64898/2026.09.08.26362522v2.full.pdf",
      "date_posted": "2026-09-28",
      "journal_link": null,
      "preprint_link": "https://www.medrxiv.org/content/10.64898/2026.09.08.26362522v2",
      "subject_category": "genetic and genomic medicine"
    }
  ]
}
```

## Run it

From code, with a Fous API key in `FOUS_API_KEY`; the answer's `data` holds the output:

```bash
curl https://api.fous.com/v1/runs \
  -H "Authorization: Bearer $FOUS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"method":"biorxiv.org/search_preprints","input":{"query":"breast cancer","server":"medrxiv","end_date":"2026-09-28","start_date":"2026-09-27","max_results":5}}'
```

From an AI agent connected to the Fous MCP server: its `run` with the same method and input. To connect one, give it `set up https://fous.com/SKILL.md`.

## Ask your agent

- Find recent preprints on CRISPR off-target effects posted in the last two months on biorxiv.org
- Search medRxiv for long COVID cognitive symptoms preprints from March 2025 through June 2025, newest first
- Show me up to 10 bioRxiv preprints about single-cell RNA sequencing of the tumor microenvironment posted between 2024-01-01 and 2024-06-30
- I need preprints mentioning antibiotic resistance plasmids in both bioRxiv and medRxiv from the past 30 days, limited to 15 results
- Look for medRxiv papers on wearable sensors for detecting atrial fibrillation, posted 2025-09-01 to 2025-09-29, with journal and DOI details

## Input schema

```json
{
  "type": "object",
  "required": [
    "query"
  ],
  "properties": {
    "query": {
      "type": "string",
      "minLength": 1,
      "description": "Topic words to find in preprint titles, abstracts, and subject categories, for example gut microbiome depression."
    },
    "server": {
      "enum": [
        "both",
        "biorxiv",
        "medrxiv"
      ],
      "type": "string",
      "default": "both",
      "description": "Preprint server to search: both, biorxiv or medrxiv."
    },
    "end_date": {
      "type": "string",
      "description": "Last posting date, inclusive, as YYYY-MM-DD, for example 2026-09-29. Defaults to today."
    },
    "start_date": {
      "type": "string",
      "description": "First posting date, inclusive, as YYYY-MM-DD, for example 2026-09-01. Defaults to 30 days before today."
    },
    "max_results": {
      "type": "integer",
      "default": 20,
      "maximum": 100,
      "minimum": 1,
      "description": "Maximum number of matching preprints, for example 20."
    }
  }
}
```

## Output schema

```json
{
  "type": "object",
  "required": [
    "preprints"
  ],
  "properties": {
    "preprints": {
      "type": "array",
      "items": {
        "type": "object",
        "required": [
          "title",
          "authors",
          "date_posted",
          "server",
          "subject_category",
          "abstract",
          "pdf_link",
          "preprint_link",
          "journal",
          "journal_link",
          "doi"
        ],
        "properties": {
          "doi": {
            "type": "string",
            "description": "Preprint DOI.",
            "x-fous-developer": true
          },
          "title": {
            "type": "string",
            "description": "Preprint title."
          },
          "server": {
            "type": "string",
            "description": "bioRxiv or medRxiv."
          },
          "authors": {
            "type": "string",
            "description": "Authors as credited by the preprint server."
          },
          "journal": {
            "type": [
              "string",
              "null"
            ],
            "description": "Journal name if subsequently published."
          },
          "abstract": {
            "type": "string",
            "description": "Plain-text abstract."
          },
          "pdf_link": {
            "type": "string",
            "description": "Direct link to the preprint PDF."
          },
          "date_posted": {
            "type": "string",
            "format": "date",
            "description": "Date this version was posted."
          },
          "journal_link": {
            "type": [
              "string",
              "null"
            ],
            "description": "Published journal article link if available."
          },
          "preprint_link": {
            "type": "string",
            "description": "Page for this preprint version."
          },
          "subject_category": {
            "type": [
              "string",
              "null"
            ],
            "description": "Subject area."
          }
        },
        "additionalProperties": false
      },
      "description": "Matching preprints, newest first."
    }
  },
  "additionalProperties": false
}
```

## See more

- [arXiv API: Search papers](https://fous.com/methods/arxiv.org/search-papers.md): Finds arXiv preprints by topic or title words, with optional author, subject, submission date range and sorting. Returns up to 100 papers with abstracts, subjects, dates and links.
- [NIH API: Search PubMed articles](https://fous.com/methods/pubmed.ncbi.nlm.nih.gov/search-articles.md): Finds PubMed medical and life-science articles by topic, with publication details and free full-text links when PubMed confirms them.
- [OpenAlex API: Search scholarly papers](https://fous.com/methods/openalex.org/search-papers.md): Searches OpenAlex scholarly works by topic, with optional institution, publication-year and open-access filters, ranked by relevance, citations or newest date.
- [arXiv API: List new papers](https://fous.com/methods/arxiv.org/list-new-papers.md): Lists the latest newly announced papers in an arXiv subject, in announcement order. Cross-lists are optional and replacements are excluded.
- [Britannica API: Search articles](https://fous.com/methods/britannica.com/search-articles.md): Searches Britannica for encyclopedia articles and returns their titles, short descriptions, article links and images when shown. Excludes other search formats such as videos, questions and stories.
- [Semantic Scholar API: Search papers](https://fous.com/methods/semanticscholar.org/search-papers.md): Searches Semantic Scholar for research papers in relevance order, with field of study, year range and open-access filters, returning AI one-sentence summaries, citations and free PDF links when available.
- [Bluesky API: Search posts](https://fous.com/methods/bsky.app/search-posts.md): Searches public Bluesky posts for words, optionally ordered by latest or top and filtered by date, author or language. Search indexing may lag behind new posts.
- [NIH API: Search grants](https://fous.com/methods/reporter.nih.gov/search-grants.md): Finds NIH research grants by topic, organisation, or researcher name. Searches the last five fiscal years by default.