Pull up the studies that cited a paper, learn how many there are, and sort out which ones bear on your question. Once you add the Firecrawl connector, Claude can look up who cited a study via Firecrawl Alexandria, working from the Firecrawl Research Index and from PubMed's cited-in links.
Best for
- Review authors collecting the follow-up studies to a widely cited trial.
- Academics seeing which recent work has built on their own paper.
- Graduate students tracing what came after a paper on their reading list.
Connector and data providers
Connector: the Firecrawl connector. It gives Claude Firecrawl's research tools plus every provider in Firecrawl Alexandria, and the team you authorize covers any priced call.
Data providers in Firecrawl Alexandria
| Provider | Tool | Best used for |
|---|---|---|
| Firecrawl Research Index | Find related papers | Starting from one paper, the work that cites it, the work it cites, or similar papers, ordered against your question. Each result has a title, abstract and an ID such as a PMID or arXiv number. |
| Firecrawl Research Index | Search papers | Locating the seed paper from a title or topic, optionally filtered by author, category or date range. |
| Firecrawl Research Index | Inspect paper, Read paper passages | Checking a paper's title and abstract, or pulling full-text passages relevant to your query. |
| PubMed and PMC | Related (cited in) | The number of PubMed articles that cite a PMID, and as many as 50 of them with journal, publication date, DOI and publication type for each. |
Explore Firecrawl Alexandria data providers across categories
Starter prompt
This one uses the Pfizer-BioNTech vaccine trial. Change the title and PMID to your own study:
Use Firecrawl to find the papers citing "Safety and Efficacy of the BNT162b2
mRNA Covid-19 Vaccine" (NEJM 2020, PMID 33301246). Check PubMed and PMC and
the Firecrawl Research Index in Firecrawl Alexandria, and tell me each
tool's price before running it.
Report back with:
- The number of PubMed articles citing it, plus the 20 most recent with
journal, publication date and PMID.
- Citing papers from the Firecrawl Research Index that relate to boosters
in older adults, each with a one-sentence abstract summary.
- Any citing papers PubMed labels as reviews.
Don't add papers the tools didn't return, and give an ID for each one.Before you start
- Connect Firecrawl. From the Firecrawl connector listing, select Connect, and Claude hands you to Firecrawl's sign-in page, where a new account is free; select the team whose credits Claude should use, then allow the connection. No API key or MCP server is involved, and Firecrawl in Claude walks through it.
- Switch it on in your chat. In the + menu, open Connectors and enable Firecrawl for the conversation.
- Know your seed paper. A PMID, DOI or the full title stops Claude from picking a different paper with a similar name.
Limitations of using Claude to find papers that cite a study
Listing who cited a paper takes a citation database, and Claude doesn't have one built in. Six problems come with that.
- Citations to papers nobody wrote. In a 2024 test against published systematic reviews, 28.6% of the references GPT-4 produced were hallucinated, and the authors say any reference a language model generates needs checking (JMIR, 2024). Anthropic says Claude can also produce incorrect or misleading responses, including quotes that look authoritative but "are not grounded in fact" (Anthropic).
- This year's citing work isn't in training data. Each Claude model has a knowledge cutoff and may not know about anything published after it (Anthropic). New papers that cite a study are what a forward search exists to find.
- Scholar's "Cited by" list isn't open to bulk use. Google Scholar doesn't offer bulk access, caps any search at 1,000 results and asks automated software to follow its robots.txt (Google Scholar), so a web search only sees part of the list.
- Scopus and Web of Science sit behind subscriptions. Both are subscription-based databases (UT Southwestern), so Claude can only reach them if you can.
- Counts disagree from one database to the next. Because each source indexes different journals, the times-cited figure varies (same UT Southwestern guide), and Google Scholar includes theses and some sources that aren't peer reviewed (UC San Diego). Claude's answers also depend on the quality of the sources it reads (Anthropic).
- A preprint and its journal version count separately. UC San Diego notes their metrics may not be merged and each can have its own citation count (UC San Diego), which means a search on one version can overlook citations of the other.
How it works
A request for citing papers runs through these parts:
- Firecrawl Alexandria: a single place where AI agents get licensed and indexed data. It brings together 100+ official providers, compensated under agreement for each use, and four Firecrawl-run indexes covering the web, scientific literature, developer sources and government material. In an 845-task comparison (one model, unchanged prompts, a blind AI judge), the Firecrawl Alexandria agents beat the built-in-web-tools agents by 21% on graded answer quality.
- The Firecrawl Research Index: a paper index that spans biomedical, life-science and clinical literature (PubMed, bioRxiv, medRxiv) together with arXiv. Given a seed paper, its related-papers tool returns citers, references or similar work.
- NCBI's cited-in links: the PubMed and PMC tool reads which PubMed articles cite a given PMID and reports the full total. The newest citing articles were first in the batch our Oct 9, 2026 API test returned.
- A traceable ID on each paper: results carry a PMID, PMCID, DOI or arXiv ID, which you can open to confirm the paper is real.
Finding citing papers in Claude with and without Firecrawl Alexandria
| Connector off | Connector on | |
|---|---|---|
| Source of the citing papers | Training data plus pages web search turns up | PubMed's cited-in records and the Firecrawl Research Index, checked at the time you ask |
| Total citations | An estimate or a figure lifted from a page | PubMed's tally, which stood at 9,028 citing articles for the BNT162b2 trial on Oct 9, 2026 |
| Newest citing work | Bounded by the training cutoff | Recently published citing articles, dated |
| Whether the paper is real | Needs checking by hand | An identifier comes with every result |
| Focusing on your question | Rewording the prompt | Citers sorted by fit to your topic, abstracts included |
| Source | Often unclear | PubMed and PMC plus the Firecrawl Research Index, part of a Firecrawl Alexandria catalog of 100+ providers and indexes spanning many subjects. Explore the catalog |
Build your own forward citation search
Frame the request around the output you need. If you're screening studies for a review:
Use Firecrawl to count the PubMed articles citing PMID 33301246, then list
the 50 most recent with title, journal, date, PMID and publication type.
Mark the reviews and meta-analyses.If you're an ML researcher mapping a paper's background:
With Firecrawl, look up "Attention Is All You Need" in the Firecrawl
Research Index and list the papers it cites on neural machine translation,
each with its arXiv ID and a short summary of the abstract.When the prompt pins down one paper and the fields to return, Claude can match it to the right tool on the first try.
Take it further
Order citers by relevance
Use Firecrawl to pull papers from the Firecrawl Research Index that cite the
NEJM 2020 BNT162b2 phase 3 trial, ranked for lipid nanoparticle delivery.
Show title, ID and the main claim of each abstract.Confirm a paper's details
With Firecrawl, inspect "A Multi-Scale Attention-based Reconstruction Fusion
Network for Motor Imagery Classification" in the Firecrawl Research Index
and give me its exact title and abstract.Quote from the full text
Use Firecrawl to read "Attention Is All You Need" from the Firecrawl
Research Index and quote what it says about multi-head attention.See prices first
Use Firecrawl to list the tools that find citing papers for a study, with
the price of each, and don't run any yet.What it costs
There's no charge to search the catalog or check a price. Credits leave your Firecrawl team only when Claude runs a priced tool, and the Firecrawl pricing page covers each plan. The Firecrawl Research Index tools carry a 0-credit price, and our direct API calls to them on Oct 9, 2026 cost nothing.
| Tool | Shows | Credits per call |
|---|---|---|
| Find related papers (Research Index) | Citing papers, references or similar work for one paper | 0 |
| Search papers (Research Index) | The indexed paper behind a title or topic | 0 |
| Inspect paper and Read paper passages (Research Index) | An abstract, or full-text passages | 0 |
| Related, cited in (PubMed and PMC) | The citing-article count for a PMID and up to 50 records | 5 |
Claude lists the tools it called and their credit cost when it answers.
[ Citing papers in Claude ]
Add Firecrawl to Claude and see which papers cite any study. Looking up the tools costs nothing.
Related use cases
- How to search arXiv and PubMed in Claude: track down the seed paper and its neighbours by topic first.
- PubMed and PMC references: the cited-in tool also runs backwards, listing the references of a paper that PubMed holds.
- OpenReview: look through public reviews and discussion of machine learning conference submissions at venues like ICLR that publish them.
Coverage limits
- Only PubMed-indexed citers count. PubMed's figure leaves out citing work it doesn't index, such as theses, books and papers in journals outside PubMed. Each call returns the total and at most 50 records.
- The Research Index returns a subset. It found 130 citing papers for the BNT162b2 trial where PubMed counted 9,028, all of them records from 2026, and only 21 for "Attention Is All You Need", every one biomedical with no arXiv papers among them. Lean on PubMed for totals and on the Research Index for ranking.
- Passages aren't always there. The passage tool worked on an arXiv paper but returned nothing for the PubMed records we tried, so some papers give you only an abstract.