How to send POST data with wget

Sending POST request bodies with wget is useful for simple API checks, form submissions, and webhook tests that do not need a heavier HTTP client. The command can send the body and print the server response in the same terminal run.

Use --post-data for short inline bodies and --post-file when the payload is easier to keep in a regular file. Add --header when the server expects a specific Content-Type, such as application/json.

GNU wget still does not implement multipart/form-data, so browser-style form uploads need another client. Keep secrets out of inline shell history when possible, and use a regular file for reusable payloads because wget needs to know the POST body size before it sends the request.

1. Send a short URL-encoded form body with --post-data.

   $ wget -qO- --post-data='project=docs&role=reviewer' https://httpbin.org/post
   {
     "args": {},
     "data": "",
     "files": {},
     "form": {
       "project": "docs",
       "role": "reviewer"
     },
     "headers": {
       "Accept": "*/*",
       "Accept-Encoding": "identity",
       "Content-Length": "26",
       "Content-Type": "application/x-www-form-urlencoded",
   ##### snipped #####
     "url": "https://httpbin.org/post"
   }

   The echoed form object and Content-Type confirm that the server received a normal URL-encoded POST body.

2. Create a payload file when the body is longer or easier to review outside the command line.

   $ cat > post-body.json <<'EOF'
   {
     "project": "docs",
     "profile": "staging"
   }
   EOF

   --post-file must read from a regular file because wget needs the request body length before it starts the POST request.

3. Send the file contents with --post-file and the matching JSON Content-Type header.

   $ wget -qO- --header='Content-Type: application/json' --post-file=post-body.json https://httpbin.org/post
   {
     "args": {},
     "data": "{\n  \"project\": \"docs\",\n  \"profile\": \"staging\"\n}\n",
     "files": {},
     "form": {},
     "headers": {
       "Accept": "*/*",
       "Accept-Encoding": "identity",
       "Content-Length": "48",
       "Content-Type": "application/json",
   ##### snipped #####
     },
     "json": {
       "profile": "staging",
       "project": "docs"
     },
   ##### snipped #####
     "url": "https://httpbin.org/post"
   }

   The echoed json object confirms that the file contents and the explicit Content-Type reached the server as intended.

4. Remove the temporary payload file after the test finishes.

   $ rm -f post-body.json