---
title: "DOI Lookup: Paper Metadata and Citation Counts"
method: GET
path: "/v1/doi-lookup"
tags: ["DOI"]
---

# DOI Lookup: Paper Metadata and Citation Counts

`GET /v1/doi-lookup`

## Request

- Base URL: `https://api.ambolt.dev`
- URL: `https://api.ambolt.dev/v1/doi-lookup`
- Auth: none required

Scholarly metadata by DOI, or a best-match search by citation text: title, authors, journal, year, publisher, citation count, licence links and URL. Bibliographic facts only.

## Query parameters

- `doi` string: DOI, e.g. 10.1038/nature14539.
- `query` string: Citation or title text to search when no DOI is known.
- `limit` integer: Maximum search results.
- `free` '1'

## Response `200`

Result (JSON). Every result names its source and the time it was read.

- object

## Other responses

- `400`: Invalid input; not charged.
- `402`: Payment required: 0.003 USD in USDC (x402 v2).

---

[API](https://skmtc.dev/ambolt/apis/ambolt-data-tools.md) · [All operations](https://skmtc.dev/ambolt/apis/ambolt-data-tools/llms.txt) · [OpenAPI document](https://skmtc.dev/ambolt/apis/ambolt-data-tools/revisions/8397885dd82f?raw)