Overview

curl wraps libcurl — the most widely deployed HTTP client library in the world. It supports HTTP/1.1, HTTP/2, HTTPS/TLS, Basic and Bearer auth, file upload/download, cookies, redirects, and a reusable handle model for connection pooling.

Use curl when you need raw HTTP power beyond what the built-in http-client offers: multipart uploads, custom TLS settings, FTP, persistent connections, or fine-grained timeout control.

Quick Start

uses curl;

var r := Get('https://api.github.com/repos/torvalds/linux');
if IsOK(r) then
  WriteLn(r.Body)
else
  WriteLn('Error ', r.StatusCode, ': ', r.Error);

GET / POST / PUT / DELETE

// Simple GET
var r := Get('https://httpbin.org/get');

// POST JSON
var r := PostJSON('https://api.example.com/users',
  '{"name":"Alice","email":"alice@example.com"}');

// PUT JSON
var r := PutJSON('https://api.example.com/users/42',
  '{"name":"Alice Updated"}');

// PATCH
var r := PatchJSON('https://api.example.com/users/42',
  '{"email":"new@example.com"}');

// DELETE
var r := Delete('https://api.example.com/users/42');

WriteLn(r.StatusCode, ' — ', Length(r.Body), ' bytes');

Custom Headers

// Headers string: "Name: Value\nName2: Value2"
var headers := BuildHeaders([
  'Authorization', 'Bearer my-token',
  'X-Request-Id',  '12345',
  'Accept',        'application/json'
]);

var r := GetH('https://api.example.com/data', headers);
var r := PostJSONH('https://api.example.com/data', body, headers);

Authentication

// Basic auth
var r := GetBasicAuth('https://api.example.com/private', 'user', 'pass');

// Bearer token
var r := GetBearer('https://api.example.com/me', 'eyJhbGci...');
var r := PostJSONBearer('https://api.example.com/data', body, token);

File Transfer

// Download file
DownloadFile('https://example.com/report.pdf', '/tmp/report.pdf');
DownloadFileBearer('https://api.example.com/export.csv', '/tmp/export.csv', token);

// Upload via multipart form
var r := UploadFile('https://api.example.com/upload', '/tmp/photo.jpg', 'file');

// Upload with extra form fields
var r := UploadFileEx(
  'https://api.example.com/upload',
  '/tmp/photo.jpg', 'file',
  'title=My Photo\ndescription=Vacation',
  headers
);

Reusable Handle (connection pooling)

// One handle reuses TCP connections — much faster for many requests
var h := NewHandle;
SetTimeout(h, 10);
SetUserAgent(h, 'MyApp/1.0');

for I := 0 to Length(urls) - 1 do begin
  var r := Perform(h, 'GET', urls[I], '', '', '');
  WriteLn(urls[I], ' → ', r.StatusCode);
end;

FreeHandle(h);

URL Encoding

var encoded := URLEncode('hello world & more');  // hello+world+%26+more
var decoded := URLDecode(encoded);