An HTTP client, taking inspiration from Ruby’s faraday and Python’s requests

Package API:

  • HttpClient - Main interface to making HTTP requests. Synchronous requests only.
  • HttpResponse - HTTP response object, used for all responses across the different clients.
  • Paginator - Auto-paginate through requests
  • Async - Asynchronous HTTP requests - a simple interface for many URLS - whose interface is similar to HttpClient - all URLs are treated the same.
  • AsyncVaried - Asynchronous HTTP requests - accepts any number of HttpRequest objects - with a different interface than HttpClient/Async due to the nature of handling requests with different HTTP methods, options, etc.
  • HttpRequest - HTTP request object, used for AsyncVaried
  • mock() - Turn on/off mocking, via webmockr
  • auth() - Simple authentication helper
  • proxy() - Proxy helper
  • upload() - File upload helper


crul now integrates with webmockr to mock HTTP requests.


CRAN version

Dev version


the client

HttpClient is where to start

Makes a R6 class, that has all the bits and bobs you’d expect for doing HTTP requests. When it prints, it gives any defaults you’ve set. As you update the object you can see what’s been set

You can also pass in curl options when you make HTTP requests, see below for examples.

do some http

The client object created above has http methods that you can call, and pass paths to, as well as query parameters, body values, and any other curl options.

Here, we’ll do a GET request on the route /get on our base url (the full url is then

The response from a http request is another R6 class HttpResponse, which has slots for the outputs of the request, and some functions to deal with the response:

Status code

Status information

The content

HTTP method

Request headers

Response headers

And you can parse the content with parse()

curl options

Asynchronous requests

The simpler interface allows many requests (many URLs), but they all get the same options/headers, etc. and you have to use the same HTTP method on all of them:

(cc <- Async$new(
  urls = c(
#> <crul async connection> 
#>   urls: 
res <- cc$get()
lapply(res, function(z) z$parse("UTF-8"))
#> [[1]]
#> [1] "<!DOCTYPE html>\n<html>\n<head>\n  <meta http-equiv='content-type' value='text/html;charset=utf8'>\n  <meta name='generator' value='Ronn/v0.7.3 ('>\n  <title>httpbin(1): HTTP Client Testing Service</title>\n  <style type='text/css' media='all'>\n  /* style: man */\n  body#manpage {margin:0}\n  .mp {max-width:100ex;padding:0 9ex 1ex 4ex}\n  .mp p,.mp pre,.mp ul,.mp ol,.mp dl {margin:0 0 20px 0}\n  .mp h2 {margin:10px 0 0 0}\n  .mp > p,.mp > pre,.mp > ul,.mp > ol,.mp > dl {margin-left:8ex}\n  .mp h3 {margin:0 0 0 4ex}\n  .mp dt {margin:0;clear:left}\n  .mp dt.flush {float:left;width:8ex}\n  .mp dd {margin:0 0 0 9ex}\n  .mp h1,.mp h2,.mp h3,.mp h4 {clear:left}\n  .mp pre {margin-bottom:20px}\n  .mp pre+h2,.mp pre+h3 {margin-top:22px}\n  .mp h2+pre,.mp h3+pre {margin-top:5px}\n  .mp img {display:block;margin:auto}\n  .mp {display:none}\n  .mp,.mp code,.mp pre,.mp tt,.mp kbd,.mp samp,.mp h3,.mp h4 {font-family:monospace;font-size:14px;line-height:1.42857142857143}\n  .mp h2 {font-size:16px;line-height:1.25}\n  .mp h1 {font-size:20px;line-height:2}\n  .mp {text-align:justify;background:#fff}\n  .mp,.mp code,.mp pre,.mp pre code,.mp tt,.mp kbd,.mp samp {color:#131211}\n  .mp h1,.mp h2,.mp h3,.mp h4 {color:#030201}\n  .mp u {text-decoration:underline}\n  .mp code,.mp strong,.mp b {font-weight:bold;color:#131211}\n  .mp em,.mp var {font-style:italic;color:#232221;text-decoration:none}\n  .mp a,.mp a:link,.mp a:hover,.mp a code,.mp a pre,.mp a tt,.mp a kbd,.mp a samp {color:#0000ff}\n  .mp {font-weight:normal;color:#434241}\n  .mp pre {padding:0 4ex}\n  .mp pre code {font-weight:normal;color:#434241}\n  .mp h2+pre,h3+pre {padding-left:0}\n, li {margin:3px 0 10px 0;padding:0;float:left;width:33%;list-style-type:none;text-transform:uppercase;color:#999;letter-spacing:1px}\n {width:100%}\n {text-align:left}\n {text-align:center;letter-spacing:4px}\n {text-align:right;float:right}\n  </style>\n  <style type='text/css' media='all'>\n  /* style: 80c */\n  .mp {max-width:86ex}\n  ul {list-style: None; margin-left: 1em!important}\n  .man-navigation {left:101ex}\n  </style>\n</head>\n\n<body id='manpage'>\n<a href=\"\"><img style=\"position: absolute; top: 0; right: 0; border: 0;\" src=\"\" alt=\"Fork me on GitHub\"></a>\n\n\n\n<div class='mp'>\n<h1>httpbin(1): HTTP Request &amp; Response Service</h1>\n<p>Freely hosted in <a href=\"\">HTTP</a>, <a href=\"\">HTTPS</a>, &amp; <a href=\"\">EU</a> flavors by <a href=\"\">Kenneth Reitz</a> &amp; <a href=\"\">Runscope</a>.</p>\n\n<h2 id=\"BONUSPOINTS\">BONUSPOINTS</h2>\n\n<ul>\n<li><a href=\"\" data-bare-link=\"true\"><code></code></a> The current time, in a variety of formats.</li>\n</ul>\n\n<h2 id=\"ENDPOINTS\">ENDPOINTS</h2>\n\n<ul>\n<li><a href=\"/\" data-bare-link=\"true\"><code>/</code></a> This page.</li>\n<li><a href=\"/ip\" data-bare-link=\"true\"><code>/ip</code></a> Returns Origin IP.</li>\n<li><a href=\"/uuid\" data-bare-link=\"true\"><code>/uuid</code></a> Returns UUID4.</li>\n<li><a href=\"/user-agent\" data-bare-link=\"true\"><code>/user-agent</code></a> Returns user-agent.</li>\n<li><a href=\"/headers\" data-bare-link=\"true\"><code>/headers</code></a> Returns header dict.</li>\n<li><a href=\"/get\" data-bare-link=\"true\"><code>/get</code></a> Returns GET data.</li>\n<li><code>/post</code> Returns POST data.</li>\n<li><code>/patch</code> Returns PATCH data.</li>\n<li><code>/put</code> Returns PUT data.</li>\n<li><code>/delete</code> Returns DELETE data</li>\n<li><a href=\"/anything\" data-bare-link=\"true\"><code>/anything</code></a> Returns request data, including method used.</li>\n<li><code>/anything/:anything</code> Returns request data, including the URL.</li>\n<li><a href=\"/encoding/utf8\"><code>/encoding/utf8</code></a> Returns page containing UTF-8 data.</li>\n<li><a href=\"/gzip\" data-bare-link=\"true\"><code>/gzip</code></a> Returns gzip-encoded data.</li>\n<li><a href=\"/deflate\" data-bare-link=\"true\"><code>/deflate</code></a> Returns deflate-encoded data.</li>\n<li><a href=\"/brotli\" data-bare-link=\"true\"><code>/brotli</code></a> Returns brotli-encoded data.</li>\n<li><a href=\"/status/418\"><code>/status/:code</code></a> Returns given HTTP Status code.</li>\n<li><a href=\"/response-headers?Server=httpbin&amp;Content-Type=text%2Fplain%3B+charset%3DUTF-8\"><code>/response-headers?key=val</code></a> Returns given response headers.</li>\n<li><a href=\"/redirect/6\"><code>/redirect/:n</code></a> 302 Redirects <em>n</em> times.</li>\n<li><a href=\"/redirect-to?\"><code>/redirect-to?url=foo</code></a> 302 Redirects to the <em>foo</em> URL.</li>\n<li><a href=\"/redirect-to?status_code=307&amp;\"><code>/redirect-to?url=foo&status_code=307</code></a> 307 Redirects to the <em>foo</em> URL.</li>\n<li><a href=\"/relative-redirect/6\"><code>/relative-redirect/:n</code></a> 302 Relative redirects <em>n</em> times.</li>\n<li><a href=\"/absolute-redirect/6\"><code>/absolute-redirect/:n</code></a> 302 Absolute redirects <em>n</em> times.</li>\n<li><a href=\"/cookies\" data-bare-link=\"true\"><code>/cookies</code></a> Returns cookie data.</li>\n<li><a href=\"/cookies/set?k1=v1&amp;k2=v2\"><code>/cookies/set?name=value</code></a> Sets one or more simple cookies.</li>\n<li><a href=\"/cookies/delete?k1=&amp;k2=\"><code>/cookies/delete?name</code></a> Deletes one or more simple cookies.</li>\n<li><a href=\"/basic-auth/user/passwd\"><code>/basic-auth/:user/:passwd</code></a> Challenges HTTPBasic Auth.</li>\n<li><a href=\"/hidden-basic-auth/user/passwd\"><code>/hidden-basic-auth/:user/:passwd</code></a> 404'd BasicAuth.</li>\n<li><a href=\"/digest-auth/auth/user/passwd/MD5/never\"><code>/digest-auth/:qop/:user/:passwd/:algorithm</code></a> Challenges HTTP Digest Auth.</li>\n<li><a href=\"/digest-auth/auth/user/passwd/MD5/never\"><code>/digest-auth/:qop/:user/:passwd</code></a> Challenges HTTP Digest Auth.</li>\n<li><a href=\"/stream/20\"><code>/stream/:n</code></a> Streams <em>min(n, 100)</em> lines.</li>\n<li><a href=\"/delay/3\"><code>/delay/:n</code></a> Delays responding for <em>min(n, 10)</em> seconds.</li>\n<li><a href=\"/drip?code=200&amp;numbytes=5&amp;duration=5\"><code>/drip?numbytes=n&amp;duration=s&amp;delay=s&amp;code=code</code></a> Drips data over a duration after an optional initial delay, then (optionally) returns with the given status code.</li>\n<li><a href=\"/range/1024\"><code>/range/1024?duration=s&amp;chunk_size=code</code></a> Streams <em>n</em> bytes, and allows specifying a <em>Range</em> header to select a subset of the data. Accepts a <em>chunk_size</em> and request <em>duration</em> parameter.</li>\n<li><a href=\"/html\" data-bare-link=\"true\"><code>/html</code></a> Renders an HTML Page.</li>\n<li><a href=\"/robots.txt\" data-bare-link=\"true\"><code>/robots.txt</code></a> Returns some robots.txt rules.</li>\n<li><a href=\"/deny\" data-bare-link=\"true\"><code>/deny</code></a> Denied by robots.txt file.</li>\n<li><a href=\"/cache\" data-bare-link=\"true\"><code>/cache</code></a> Returns 200 unless an If-Modified-Since or If-None-Match header is provided, when it returns a 304.</li>\n<li><a href=\"/etag/etag\"><code>/etag/:etag</code></a> Assumes the resource has the given etag and responds to If-None-Match header with a 200 or 304 and If-Match with a 200 or 412 as appropriate.</li>\n<li><a href=\"/cache/60\"><code>/cache/:n</code></a> Sets a Cache-Control header for <em>n</em> seconds.</li>\n<li><a href=\"/bytes/1024\"><code>/bytes/:n</code></a> Generates <em>n</em> random bytes of binary data, accepts optional <em>seed</em> integer parameter.</li>\n<li><a href=\"/stream-bytes/1024\"><code>/stream-bytes/:n</code></a> Streams <em>n</em> random bytes of binary data in chunked encoding, accepts optional <em>seed</em> and <em>chunk_size</em> integer parameters.</li>\n<li><a href=\"/links/10\"><code>/links/:n</code></a> Returns page containing <em>n</em> HTML links.</li>\n<li><a href=\"/image\"><code>/image</code></a> Returns page containing an image based on sent Accept header.</li>\n<li><a href=\"/image/png\"><code>/image/png</code></a> Returns a PNG image.</li>\n<li><a href=\"/image/jpeg\"><code>/image/jpeg</code></a> Returns a JPEG image.</li>\n<li><a href=\"/image/webp\"><code>/image/webp</code></a> Returns a WEBP image.</li>\n<li><a href=\"/image/svg\"><code>/image/svg</code></a> Returns a SVG image.</li>\n<li><a href=\"/forms/post\" data-bare-link=\"true\"><code>/forms/post</code></a> HTML form that submits to <em>/post</em></li>\n<li><a href=\"/xml\" data-bare-link=\"true\"><code>/xml</code></a> Returns some XML</li>\n</ul>\n\n<h2 id=\"DESCRIPTION\">DESCRIPTION</h2>\n\n<p>Testing an HTTP Library can become difficult sometimes. <a href=\"\">RequestBin</a> is fantastic for testing POST requests, but doesn't let you control the response. This exists to cover all kinds of HTTP scenarios. Additional endpoints are being considered.</p>\n\n<p>All endpoint responses are JSON-encoded.</p>\n\n<h2 id=\"EXAMPLES\">EXAMPLES</h2>\n\n<h3 id=\"-curl-http-httpbin-org-ip\">$ curl</h3>\n\n<pre><code>{\"origin\": \"\"}\n</code></pre>\n\n<h3 id=\"-curl-http-httpbin-org-user-agent\">$ curl</h3>\n\n<pre><code>{\"user-agent\": \"curl/7.19.7 (universal-apple-darwin10.0) libcurl/7.19.7 OpenSSL/0.9.8l zlib/1.2.3\"}\n</code></pre>\n\n<h3 id=\"-curl-http-httpbin-org-get\">$ curl</h3>\n\n<pre><code>{\n   \"args\": {},\n   \"headers\": {\n      \"Accept\": \"*/*\",\n      \"Connection\": \"close\",\n      \"Content-Length\": \"\",\n      \"Content-Type\": \"\",\n      \"Host\": \"\",\n      \"User-Agent\": \"curl/7.19.7 (universal-apple-darwin10.0) libcurl/7.19.7 OpenSSL/0.9.8l zlib/1.2.3\"\n   },\n   \"origin\": \"\",\n   \"url\": \"\"\n}\n</code></pre>\n\n<h3 id=\"-curl-I-http-httpbin-org-status-418\">$ curl -I</h3>\n\n<pre><code>HTTP/1.1 418 I'M A TEAPOT\nServer: nginx/0.7.67\nDate: Mon, 13 Jun 2011 04:25:38 GMT\nConnection: close\nx-more-info:\nContent-Length: 135\n</code></pre>\n\n<h3 id=\"-curl-https-httpbin-org-get-show_env-1\">$ curl</h3>\n\n<pre><code>{\n  \"headers\": {\n    \"Content-Length\": \"\",\n    \"Accept-Language\": \"en-US,en;q=0.8\",\n    \"Accept-Encoding\": \"gzip,deflate,sdch\",\n    \"X-Forwarded-Port\": \"443\",\n    \"X-Forwarded-For\": \"\",\n    \"Host\": \"\",\n    \"Accept\": \"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\",\n    \"User-Agent\": \"Mozilla/5.0 (X11; Linux i686) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.83 Safari/535.11\",\n    \"X-Request-Start\": \"1350053933441\",\n    \"Accept-Charset\": \"ISO-8859-1,utf-8;q=0.7,*;q=0.3\",\n    \"Connection\": \"keep-alive\",\n    \"X-Forwarded-Proto\": \"https\",\n    \"Cookie\": \"_gauges_unique_day=1; _gauges_unique_month=1; _gauges_unique_year=1; _gauges_unique=1; _gauges_unique_hour=1\",\n    \"Content-Type\": \"\"\n  },\n  \"args\": {\n    \"show_env\": \"1\"\n  },\n  \"origin\": \"\",\n  \"url\": \"\"\n}\n</code></pre>\n\n<h2 id=\"Installing-and-running-from-PyPI\">Installing and running from PyPI</h2>\n\n<p>You can install httpbin as a library from PyPI and run it as a WSGI app.  For example, using Gunicorn:</p>\n\n<pre><code class=\"bash\">$ pip install httpbin\n$ gunicorn httpbin:app\n</code></pre>\n\n\n<h2 id=\"AUTHOR\">AUTHOR</h2>\n\n<p>A <a href=\"\">Kenneth Reitz</a> project.</p>\n<p>BTC: <a href=\"\"><code>1Me2iXTJ91FYZhrGvaGaRDCBtnZ4KdxCug</code></a></p>\n\n<h2 id=\"SEE-ALSO\">SEE ALSO</h2>\n\n<p><a href=\"\"></a> - Make HTTP requests.</p>\n<p><a href=\"\">RequestBin</a> - Inspect HTTP requests.</p>\n<p><a href=\"\" data-bare-link=\"true\"></a></p>\n\n</div>\n\n\n    \n<script type=\"text/javascript\">\n  (function() {\n    window._pa = window._pa || {};\n    _pa.productId = \"httpbin\";\n    var pa = document.createElement('script'); pa.type = 'text/javascript'; pa.async = true;\n    pa.src = ('https:' == document.location.protocol ? 'https:' : 'http:') + \"//\";\n    var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(pa, s);\n  })();\n</script>\n\n<script type=\"text/javascript\">\n  var _gauges = _gauges || [];\n  (function() {\n    var t   = document.createElement('script');\n    t.type  = 'text/javascript';\n    t.async = true;\n    = 'gauges-tracker';\n    t.setAttribute('data-site-id', '58cb2e71c88d9043ac01d000');\n    t.setAttribute('data-track-path', '');\n    t.src = '';\n    var s = document.getElementsByTagName('script')[0];\n    s.parentNode.insertBefore(t, s);\n  })();\n</script>\n\n\n</body>\n</html>"
#> [[2]]
#> [1] "{\n  \"args\": {\n    \"a\": \"5\"\n  }, \n  \"headers\": {\n    \"Accept\": \"application/json, text/xml, application/xml, */*\", \n    \"Accept-Encoding\": \"gzip, deflate\", \n    \"Connection\": \"close\", \n    \"Host\": \"\", \n    \"User-Agent\": \"libcurl/7.54.0 r-curl/3.1 crul/\"\n  }, \n  \"origin\": \"\", \n  \"url\": \"\"\n}\n"
#> [[3]]
#> [1] "{\n  \"args\": {\n    \"foo\": \"bar\"\n  }, \n  \"headers\": {\n    \"Accept\": \"application/json, text/xml, application/xml, */*\", \n    \"Accept-Encoding\": \"gzip, deflate\", \n    \"Connection\": \"close\", \n    \"Host\": \"\", \n    \"User-Agent\": \"libcurl/7.54.0 r-curl/3.1 crul/\"\n  }, \n  \"origin\": \"\", \n  \"url\": \"\"\n}\n"

The AsyncVaried interface accepts any number of HttpRequest objects, which can define any type of HTTP request of any HTTP method:

Execute the requests

Then functions get applied to all responses:


http caching

Add integration for:

for flexible and easy HTTP request caching


  • Please report any issues or bugs.
  • License: MIT
  • Get citation information for crul in R doing citation(package = 'crul')
  • Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms.