HTTPie

HTTPie is a command line HTTP client, just like curl but more user friendly.

Windows - can be installed with pip (requires Python 3.x installed). By the way, this is cross-platform solution.
Linux - can be installed with built-in package manager or Homebrew.
macOS - can be installed with Homebrew or MacPorts.

Check docs for installation details.

Usage

http <url> <body params>

for Bash/Zsh/etc.

# Optional flags and method were omitted:
# if unspecified method is set to POST if body is specified
# -j/--json forces JSON mode, yet it's default behavior
http "https://discord.com/api/webhooks/123/w3bh00k_t0k3n" content="test" embeds[0][title]="text"

Depends on type of value you have to use different separators:

= - text.
:= - raw JSON value. Use it for array, number, boolean and nested values.
@ - embed file.
=@ - embed json file.

http \
  "https://discord.com/api/webhooks/123/w3bh00k_t0k3n" \
  content="test" \
  embeds[0][title]="text"

Also, if you don't want to mess with these and would like to just pass raw body, like can be done in curl, use the next approach:

echo -n '{"content": "test", "embeds": [{"title": "text"}]}' | http "https://discord.com/api/webhooks/123/w3bh00k_t0k3n"

PowerShell

$WEBHOOK_URL = "https://discord.com/api/webhooks/123/w3bh00k_t0k3n"
http $WEBHOOK_URL content="test" embeds[0][title]="text"
# Also you can just pass raw json body:
'{"content": "test", "embeds": [{"title": "text"}]}' | http $WEBHOOK_URL

Command Prompt (cmd.exe)

REM Notice escaped double quotes around values and none around link
SET WEBHOOK_URL=https://discord.com/api/webhooks/123/w3bh00k_t0k3n
http %WEBHOOK_URL% content="test" embeds[0][title]="text"

REM Outer quotes are skipped due to cmd parsing
echo {"content": "test", "embeds": [{"title": "text"}]} | http %WEBHOOK_URL%

Sending attachments