cURL website screenshot

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 publishes 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 8 more developer resources.

20.6/100 emerging ▬ flat Agent 3/100 human only Full breakdown ↓
scored 2026-07-28 · rubric v0.6
AccessFreemium
2 APIs
API ClientCommand LineData TransferFTPHTTPHTTPSLibraryNetwork ToolsOpen SourceREST

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-28 · rubric v0.6
Composite quality — 20.6/100 · emerging
Contract Quality 0.0 / 25
Developer Ergonomics 1.3 / 20
Commercial Clarity 7.9 / 20
Operational Transparency 5.5 / 13
Governance 0.0 / 12
Discoverability 5.9 / 10
Agent readiness — 3/100 · human only
Machine-Readable Contract 0 / 18
Agentic Access Contract 0 / 10
MCP Server 0 / 12
Machine-Readable Auth 0 / 10
Idempotency 0 / 9
Stable Error Semantics 0 / 8
Request/Response Examples 0 / 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
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/curl: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

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...

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

Operate 1

Status, limits, changes, and where to get help

Commercial 1

Pricing, plans, and the legal terms of use

Company 3

The organization behind the API

Other 2

Properties that don't map to a standard resource type

Source (apis.yml)

apis.yml Raw ↑
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
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/curl.png
tags:
- API Client
- Command Line
- Data Transfer
- FTP
- HTTP
- HTTPS
- Library
- Network Tools
- Open Source
- REST
created: '2024-01-01'
modified: '2026-04-28'
specificationVersion: '0.20'
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
  - 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: 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