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, use a regular file for reusable payloads because wget needs to know the POST body size before it sends the request, and check redirect responses before using POST commands in automation.

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

   $ wget --quiet --output-document=- \
     --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, JSON-shaped, 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 --quiet --output-document=- \
     --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. Check the first response status without following redirects when the POST target controls a session, payment, or webhook action.

   $ wget --server-response --quiet --output-document=/dev/null --max-redirect=0 \
     --header='Content-Type: application/json' \
     --post-file=post-body.json https://httpbin.org/post
     HTTP/1.1 200 OK
     Content-Type: application/json
     Content-Length: 582

   GNU wget handles POST redirects differently depending on the response code. Inspect the first status before trusting a command that may be replayed by a script.

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

   $ rm -f post-body.json