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ncurl

Source: R/ncurl.R
ncurl.Rd

nano cURL - a minimalist http(s) client.

Usage

ncurl(
  url,
  convert = TRUE,
  follow = FALSE,
  method = NULL,
  headers = NULL,
  data = NULL,
  response = NULL,
  timeout = NULL,
  tls = NULL
)

Arguments

url

the URL address.

convert

[default TRUE] logical value whether to attempt conversion of the received raw bytes to a character vector. Set to FALSE if downloading non-text data.

follow

[default FALSE] logical value whether to automatically follow redirects (not applicable for async requests). If FALSE, the redirect address is returned as response header 'Location'.

method

(optional) the HTTP method as a character string. Defaults to 'GET' if not specified, and could also be 'POST', 'PUT' etc.

headers

(optional) a named character vector specifying the HTTP request headers, for example:
c(Authorization = "Bearer APIKEY", "Content-Type" = "text/plain")
A non-character or non-named vector will be ignored.

data

(optional) request data to be submitted. Must be a character string or raw vector, and other objects are ignored. If a character vector, only the first element is taken. When supplying binary data, the appropriate 'Content-Type' header should be set to specify the binary format.

response

(optional) a character vector specifying the response headers to return e.g. c("date", "server"). These are case-insensitive and will return NULL if not present. Specify TRUE to return all response headers. A non-character vector will be ignored (other than TRUE).

timeout

(optional) integer value in milliseconds after which the transaction times out if not yet complete.

tls

(optional) applicable to secure HTTPS sites only, a client TLS Configuration object created by tls_config(). If missing or NULL, certificates are not validated.

Value

Named list of 3 elements:

  • $status - integer HTTP repsonse status code (200 - OK). Use status_code() for a translation of the meaning.

  • $headers - named list of response headers (all headers if response = TRUE, or those specified in response, or NULL otherwise). If the status code is within the 300 range, i.e. a redirect, the response header 'Location' is automatically appended to return the redirect address.

  • $data - the response body, as a character string if convert = TRUE (may be further parsed as html, json, xml etc. as required), or a raw byte vector if FALSE (use writeBin() to save as a file).

Public Internet HTTPS

When making HTTPS requests over the public internet, you should supply a TLS configuration to validate server certificates. See tls_config() for details.

See also

ncurl_aio() for asynchronous http requests; ncurl_session() for persistent connections.

Examples

ncurl(
  "https://postman-echo.com/get",
  convert = FALSE,
  response = c("date", "content-type"),
  timeout = 1200L
)
#> $status
#> [1] 200
#> 
#> $headers
#> $headers$date
#> [1] "Mon, 09 Mar 2026 08:24:09 GMT"
#> 
#> $headers$`content-type`
#> [1] "application/json; charset=utf-8"
#> 
#> 
#> $data
#>   [1] 7b 22 61 72 67 73 22 3a 7b 7d 2c 22 68 65 61 64 65 72 73 22 3a 7b
#>  [23] 22 68 6f 73 74 22 3a 22 70 6f 73 74 6d 61 6e 2d 65 63 68 6f 2e 63
#>  [45] 6f 6d 22 2c 22 61 63 63 65 70 74 2d 65 6e 63 6f 64 69 6e 67 22 3a
#>  [67] 22 67 7a 69 70 2c 20 62 72 22 2c 22 78 2d 66 6f 72 77 61 72 64 65
#>  [89] 64 2d 70 72 6f 74 6f 22 3a 22 68 74 74 70 73 22 7d 2c 22 75 72 6c
#> [111] 22 3a 22 68 74 74 70 73 3a 2f 2f 70 6f 73 74 6d 61 6e 2d 65 63 68
#> [133] 6f 2e 63 6f 6d 2f 67 65 74 22 7d
#> 
ncurl(
  "https://postman-echo.com/get",
  response = TRUE,
  timeout = 1200L
)
#> $status
#> [1] 200
#> 
#> $headers
#> $headers$Date
#> [1] "Mon, 09 Mar 2026 08:24:10 GMT"
#> 
#> $headers$`Content-Type`
#> [1] "application/json; charset=utf-8"
#> 
#> $headers$`Content-Length`
#> [1] "143"
#> 
#> $headers$Connection
#> [1] "close"
#> 
#> $headers$`CF-RAY`
#> [1] "9d98ae867a5046a1-DFW"
#> 
#> $headers$etag
#> [1] "W/\"8f-7zN8nSad8A9WlFJjKQZB04z5nHE\""
#> 
#> $headers$vary
#> [1] "Accept-Encoding"
#> 
#> $headers$`Set-Cookie`
#> [1] "sails.sid=s%3AhnWIcWgkSIWIasaH6ZnkIGPYdSHmyHhS.%2BCdD4YqdQd6kuNbKfscmxhFaR0ACIGbi2rxrP8rqQtA; Path=/; HttpOnly, __cf_bm=XTPLuI7CPnZG0EGhJzYYGsbKjpaTswujA86GxwY5l3Q-1773044650-1.0.1.1-zWl59QY8FVuBUSg_quayPWeENuuVldgnUNyW18_BvFpnq_zoxjN_BgxqdJwoLSo3rTBy0TVR_zZqdrjLy_ps7LzaY.uxiWBo__.ouBYsg2w; path=/; expires=Mon, 09-Mar-26 08:54:10 GMT; domain=.postman-echo.com; HttpOnly; Secure, _cfuvid=OLrXWPFO94KUAIjP78RgKV07iQ5._eSNKLrvDW0u4.s-1773044650038-0.0.1.1-604800000; path=/; domain=.postman-echo.com; HttpOnly; Secure; SameSite=None"
#> 
#> $headers$`x-envoy-upstream-service-time`
#> [1] "5"
#> 
#> $headers$`cf-cache-status`
#> [1] "DYNAMIC"
#> 
#> $headers$Server
#> [1] "cloudflare"
#> 
#> 
#> $data
#> [1] "{\"args\":{},\"headers\":{\"host\":\"postman-echo.com\",\"accept-encoding\":\"gzip, br\",\"x-forwarded-proto\":\"https\"},\"url\":\"https://postman-echo.com/get\"}"
#> 
ncurl(
  "https://postman-echo.com/put",
  method = "PUT",
  headers = c(Authorization = "Bearer APIKEY"),
  data = "hello world",
  timeout = 1500L
)
#> $status
#> [1] 200
#> 
#> $headers
#> NULL
#> 
#> $data
#> [1] "{\"args\":{},\"data\":\"hello world\",\"files\":{},\"form\":{},\"headers\":{\"host\":\"postman-echo.com\",\"authorization\":\"Bearer APIKEY\",\"accept-encoding\":\"gzip, br\",\"x-forwarded-proto\":\"https\",\"content-length\":\"11\",\"content-type\":\"application/json\"},\"json\":null,\"url\":\"https://postman-echo.com/put\"}"
#> 
ncurl(
  "https://postman-echo.com/post",
  method = "POST",
  headers = c(`Content-Type` = "application/json"),
  data = '{"key":"value"}',
  timeout = 1500L
)
#> $status
#> [1] 200
#> 
#> $headers
#> NULL
#> 
#> $data
#> [1] "{\"args\":{},\"data\":{\"key\":\"value\"},\"files\":{},\"form\":{},\"headers\":{\"host\":\"postman-echo.com\",\"content-type\":\"application/json\",\"accept-encoding\":\"gzip, br\",\"x-forwarded-proto\":\"https\",\"content-length\":\"15\"},\"json\":{\"key\":\"value\"},\"url\":\"https://postman-echo.com/post\"}"
#>