curl vs Invoke-WebRequest vs Invoke-RestMethod in PowerShell

In PowerShell, Invoke-WebRequest returns the raw HTTP response, Invoke-RestMethod returns the body already parsed (JSON becomes objects), and curl.exe is the native curl program. In Windows PowerShell 5.1, typing curl does not run curl at all: it is an alias for Invoke-WebRequest. CurlDotNet adds a fourth option: run the curl command text in-process with [CurlDotNet.Curl]::Execute(...).

The curl alias trap

Get-Command curl      # Windows PowerShell 5.1: Alias  curl -> Invoke-WebRequest
                      # PowerShell 7+:          Application  curl(.exe)
curl.exe --version    # always the real curl (included with Windows 10 1803 and later)

PowerShell 6 removed the curl and wget aliases, but Windows PowerShell 5.1 still ships them. A pasted curl -H "Accept: application/json" https://... in 5.1 fails with parameter-binding errors, because -H binds to Invoke-WebRequest -Headers, which expects a hashtable, not a string.

Why pasted curl commands break in PowerShell

Even when curl.exe really runs, commands written for bash often fail:

Line continuation. Bash uses \ at the end of a line. PowerShell uses a backtick. With \, PowerShell runs the first line on its own, then tries to run -H ... as a command.
Embedded double quotes. Windows PowerShell 5.1, and PowerShell 7 before 7.3, drop embedded " when passing arguments to native programs. -d '{"key":"value"}' reaches curl.exe as {key:value}. That is why Windows-oriented docs write -d '{\"key\":\"value\"}'. PowerShell 7.3 and later pass the quotes through by default (see $PSNativeCommandArgumentPassing).
Variable expansion. In double-quoted strings PowerShell expands $TOKEN itself, often to an empty string.

How CurlDotNet sidesteps all three

The command is a .NET string handed to a method, not arguments to a native process, so PowerShell’s native-argument rules never apply. Inside a single-quoted here-string PowerShell changes nothing, and CurlDotNet’s parser handles the shell syntax:

$cmd = @'
curl -X POST https://httpbin.org/post `
  -H "Content-Type: application/json" `
  -d '{"key":"value"}'
'@
$r = [CurlDotNet.Curl]::Execute($cmd)
($r.Body | ConvertFrom-Json).json.key      # value

Backtick, \ and ^ line continuations are all joined.
The JSON keeps its quotes, because no native command line is involved.
$env:NAME and $NAME are expanded from environment variables by CurlDotNet. In a single-quoted PowerShell string PowerShell leaves them alone; CurlDotNet then expands them where a shell would, unquoted or inside the curl command’s double quotes, but not inside its single quotes.
The Windows habit -d '{\"key\":\"value\"}' is unescaped to {"key":"value"} (when the quoted text contains no bare "), so the server receives valid JSON whether or not you delete the backslashes.

The same PowerShell-style command from C#, verified with 9.8.0 against httpbin.org:

using CurlDotNet;

var ps = "curl -X POST https://httpbin.org/post `\n  -H 'Content-Type: application/json' `\n  -d '{\"key\":\"value\"}'";
var result = await Curl.ExecuteAsync(ps);
Console.WriteLine(result.Body);  // "json": { "key": "value" }

Side by side

	`Invoke-WebRequest`	`Invoke-RestMethod`	`curl.exe`	CurlDotNet
Input	Cmdlet parameters	Cmdlet parameters	curl flags, subject to PowerShell quoting	curl command as one string
Output	Response object (`StatusCode`, `Content`, `Headers`)	Parsed body	Text on stdout	`CurlResult` (`StatusCode`, `Body`, `Headers`, `BinaryData`)
4xx / 5xx	Throws (PowerShell 7 adds `-SkipHttpErrorCheck`)	Throws (same switch)	Exit code 0 unless `-f`	`IsSuccess = $false`, no throw unless `-f`
JSON	`ConvertFrom-Json`	Automatic	`ConvertFrom-Json`	`ConvertFrom-Json` (or `ParseJson` in C#)
Available	Built in	Built in	Windows 10 1803+, macOS, Linux	Load the DLL
Same code in C#	No	No	No (Process.Start)	Yes

Which to use

Writing new PowerShell from scratch: Invoke-RestMethod is idiomatic, and [CurlDotNet.Curl]::ToPowershellCode() can generate it from a curl command.
Running a curl command from documentation exactly as written: CurlDotNet, or curl.exe in PowerShell 7.3+ with careful quoting.
Sharing the request between a PowerShell script and a C# app: CurlDotNet, because the string is identical in both.

The PowerShell behaviors described here are standard PowerShell; the CurlDotNet snippets in PowerShell were not run in a PowerShell session for this page.

curl vs Invoke-WebRequest vs Invoke-RestMethod (C#)