cURL

cURL is a command-line tool and library for transferring data with URLs. Originally released in 1997 by Daniel Stenberg, cURL is the de facto standard tool used by developers for testing, automating, and scripting interactions with HTTP, HTTPS, FTP, and many other URL-based protocols. It ships in two primary forms - the curl command-line binary used directly in shells and scripts, and libcurl, a portable C library that powers data transfer features inside thousands of applications, operating systems, devices, and programming languages.

cURL is listed with 2 APIs on the APIs.io network. Tagged areas include API Client, Command Line, Data Transfer, FTP, and HTTP.

cURL’s developer surface includes support, engineering blog, and 11 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

19.3/100 emerging ▬ flat Agent 2/100 human only Front door AI 1/6 silent Heartbeat 100/100 alive Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

AccessFreemium

2 APIs

API Client Command Line Data Transfer FTP HTTP LibraryNetwork ToolsOpen Source REST

Kin Score

Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0

Composite quality — 19.3/100 · emerging

Contract Quality 1.4 / 21

Developer Ergonomics 5.3 / 17

Access Clarity 1.3 / 17

Operational Transparency 4.4 / 11

Contract Governance 0.0 / 10

Discoverability 4.9 / 9

Regulatory Posture 1.8 / 15

Agent readiness — 2/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 5 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Education & Research regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Agent readiness — checks not met, largest first (exact, from this profile):

Machine-Readable Contract +18 pts — api_specs includes an OpenAPI document
MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship
Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author
Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey)
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes

11 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Contract Quality scores 6.5 — up to +23.4 composite points
Access Clarity scores 7.9 — up to +18.4 composite points
Developer Ergonomics scores 31.0 — up to +13.8 composite points

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/curl/apis.yml: open an issue on github.com/api-evangelist/curl to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Markets this provider is in provisional

The Kin Score Market layer reads a provider inside its market: its position, and how deep its integrations go. Depth is only comparable within a position. Provisional and unweighted: not part of the Kin Score or agent readiness.

Market	Position	Depth	Registered MCP server	Declares compatibility
Official CLIs on Package Managers	standard	45.0	-	-
Vulnerability Disclosure (CVE Numbering Authorities, FIRST member teams; CISA KEV exposure)	standard	45.0	-	-
OpenSSF Best Practices Badge Holders	standard	45.0	-	-

Registered MCP server and declares compatibility are report only — not weighted. Undeclared means we found nothing we can read, so there is no number: we never infer integrations.

Standards implemented 3

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

FTP

tagged — the provider's own APIs.json carries the standard as a tag; implementation not verified

HTTP

tagged — the provider's own APIs.json carries the standard as a tag; implementation not verified

REST

tagged — the provider's own APIs.json carries the standard as a tag; implementation not verified

APIs 2

Individual APIs this provider publishes, each with its own machine-readable definition.

cURL Command Line Tool

The curl command-line tool transfers data to or from a server using URL syntax, supporting protocols including DICT, FILE, FTP, FTPS, GOPHER, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDA...

libcurl

libcurl is a free, easy-to-use, thread-safe, IPv6-compatible client-side URL transfer library written in C with a stable API and ABI. It supports the same broad set of protocols...

cURL API pricing

Not yet checked against cURL's own pricing page. Compiled by API Evangelist on 2026-05-04; confirm before you rely on a figure. A free plan or tier is listed.

Plan	Price
Free freemium	Free
Professional paid	Free
Enterprise enterprise	—

Plan details, limits and sources →

Rate limits

Free Tier Default: 10 requests per minute
Free Tier Monthly Quota: 1000 requests per month
Professional Tier Default: 100 requests per minute

Compiled by API Evangelist, not yet checked against cURL's documentation. All 5 limits →

Pricing Plans 1

Published pricing tiers and plan structures.

Curl Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Curl Rate Limits

5 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Curl Finops

FINOPS

Security Posture 2

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Curl Domain Security

TLSv1.3 · HSTS

SECURITY

Curl Vulnerability Disclosure

Hackerone · security.txt · contact published

SECURITY

Resources

Access & Security 3

Authentication, authorization, and security posture

VulnerabilityDisclosure

VulnerabilityDisclosure

DomainSecurity

DomainSecurity

Security

Security

Operate 2

Status, limits, changes, and where to get help

RateLimits

RateLimits

Support

Support

Commercial 3

Pricing, plans, and the legal terms of use

Plans

Plans

FinOps

FinOps

License

License

Company 3

The organization behind the API

LinkedIn

Website

Website

Blog

Blog

Other 2

Properties that don't map to a standard resource type

Mailing Lists

Mailing Lists

Books

Books

Source (apis.yml)

aid: curl
name: cURL
description: cURL is a command-line tool and library for transferring data with URLs. Originally released in 1997 by Daniel
  Stenberg, cURL is the de facto standard tool used by developers for testing, automating, and scripting interactions with
  HTTP, HTTPS, FTP, and many other URL-based protocols. It ships in two primary forms - the curl command-line binary used
  directly in shells and scripts, and libcurl, a portable C library that powers data transfer features inside thousands of
  applications, operating systems, devices, and programming languages.
url: https://raw.githubusercontent.com/api-evangelist/curl/refs/heads/main/apis.yml
deliveryModel:
  model: unknown
  license_evidence:
    repo: curl/curl
    spdx: NOASSERTION
    stars: 42925
  open_source: unknown
  commercial: false
  callable_host: false
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - repository-unlicensed
  generated: '2026-09-25'
  method: derived
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: low
  source:
  - plans
  - security
  generated: '2026-11-06'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/curl.png
tags:
- API Client
- Command Line
- Data Transfer
- FTP
- HTTP
- Library
- Network Tools
- Open Source
- REST
tags_raw:
- API Client
- Command Line
- Data Transfer
- FTP
- HTTP
- HTTPS
- Library
- Network Tools
- Open Source
- REST
- Open-Source
created: '2024-01-01'
modified: '2026-04-28'
specificationVersion: '0.23'
apis:
- aid: curl:curl-cli
  name: cURL Command Line Tool
  description: The curl command-line tool transfers data to or from a server using URL syntax, supporting protocols including
    DICT, FILE, FTP, FTPS, GOPHER, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, MQTT, POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMB, SMTP,
    SMTPS, TELNET, TFTP, WS and WSS. It is widely used for API testing, automation, scripting, file uploads and downloads,
    debugging HTTP exchanges, and as a general-purpose network client.
  image: https://curl.se/logo/curl-logo.svg
  humanURL: https://curl.se/
  tags:
  - API Client
  - API Testing
  - Command Line
  - Data Transfer
  - FTP
  - HTTP
  - REST
  tags_raw:
  - API Client
  - API Testing
  - Command Line
  - Data Transfer
  - FTP
  - HTTP
  - HTTPS
  - REST
  properties:
  - type: Documentation
    url: https://curl.se/docs/
  - type: Manual
    url: https://curl.se/docs/manual.html
  - type: Tutorial
    url: https://curl.se/docs/tutorial.html
  - type: Man Page
    url: https://curl.se/docs/manpage.html
  - type: How To
    url: https://curl.se/docs/howto.html
  - type: FAQ
    url: https://curl.se/docs/faq.html
  - type: GitHub
    url: https://github.com/curl/curl
  - type: Download
    url: https://curl.se/download.html
  - type: ChangeLog
    url: https://curl.se/changes.html
- aid: curl:libcurl
  name: libcurl
  description: libcurl is a free, easy-to-use, thread-safe, IPv6-compatible client-side URL transfer library written in C
    with a stable API and ABI. It supports the same broad set of protocols as the curl command-line tool and is embedded in
    operating systems, applications, and developer tools across nearly every platform. Bindings are available for dozens of
    languages including PHP, Python, Ruby, Rust, Go, Java, .NET, and many others.
  image: https://curl.se/logo/curl-logo.svg
  humanURL: https://curl.se/libcurl/
  tags:
  - C
  - HTTP Client
  - Library
  - SDK
  - URL Transfer
  properties:
  - type: Documentation
    url: https://curl.se/libcurl/
  - type: APIReference
    url: https://curl.se/libcurl/c/
  - type: Examples
    url: https://curl.se/libcurl/c/example.html
  - type: SDKs
    url: https://curl.se/libcurl/bindings.html
  - type: GitHub
    url: https://github.com/curl/curl
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
common:
- type: Plans
  url: plans/curl-plans-pricing.yml
- type: RateLimits
  url: rate-limits/curl-rate-limits.yml
- type: FinOps
  url: finops/curl-finops.yml
- type: VulnerabilityDisclosure
  url: security/curl-vulnerability-disclosure.yml
- type: DomainSecurity
  url: security/curl-domain-security.yml
- type: LinkedIn
  url: https://www.linkedin.com/company/the-curl-project
- type: Website
  url: https://curl.se/
- type: Support
  url: https://curl.se/support.html
- type: Mailing Lists
  url: https://curl.se/mail/
- type: Security
  url: https://curl.se/dev/security.html
- type: Blog
  url: https://daniel.haxx.se/blog/
- type: Books
  url: https://everything.curl.dev/
- type: License
  url: https://curl.se/docs/copyright.html

cURL API — frequently asked questions

Does cURL have an API?

Yes. APIs.io lists 2 APIs from cURL, including cURL Command Line Tool and libcurl.

How much does the cURL API cost?

APIs.io lists 3 pricing plans for cURL, with each plan's price, limits and inclusions under Pricing on this page.

Is the cURL API ready for AI agents?

cURL has a Kin Score of 19.3 out of 100 (emerging) and an Agent Readiness score of 1.9 (human-only), scored by API Evangelist on 2026-11-06.

Work with this as data

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MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

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get_provider_artifactsEvery artifact this provider publishes, grouped by type.
get_provider_operationsEvery operation across all of their OpenAPIs — one call instead of parsing every spec.
get_provider_toolsEvery MCP tool they ship, with the operation each wraps.
get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
get_provider_ratingPRO — composite, band, trend and facet scores.
apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
resolveTurn a domain, URL or GitHub org into the provider it belongs to.
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