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HTTP HEAD Request Explained — Bulk Image Downloader Pro

danito

Validating five hundred image URLs by downloading every file wastes bandwidth and time. An HTTP HEAD request asks the server for metadata only—status code and headers—without transferring the image body. Here is the HTTP HEAD request explained for bulk image workflows: what it returns, when it helps, and where it falls short.

Bulk Image Downloader Pro uses HEAD as the first pass in the 404 checker on the options page.

Step 1: HEAD versus GET

Every HTTP request uses a method. GET says “send the full resource including its body.” HEAD says “send the same status and headers you would for GET, but omit the body.” You still learn whether the resource exists and what the server claims about it—without downloading image bytes.

For one small thumbnail the savings are minor. Across hundreds of URLs where each file might be hundreds of kilobytes, header-only checks prune dead links in a fraction of the time a full download would take.

Step 2: what HEAD response headers tell you

  • Status code — 200 means found; 404 means gone; 301/302 means redirected
  • Content-Type — whether the server labels the response as an image format or something else like text/html
  • Content-Length — approximate size in bytes; useful for spotting empty or placeholder responses

These headers answer the questions that matter before you queue a bulk download.

Step 3: how the 404 checker uses HEAD

Paste a URL list into the 404 checker. It fires HEAD requests in batches. When HEAD fails, returns 403/405, or is not OK, the checker retries with GET (with a small byte range). URLs that pass status and format checks land in the reachable list; failures go to unreachable. Copy or download the reachable set and paste it into a download task yourself—there is no automatic re-import from checker results.

Step 4: when HEAD results need skepticism

Not every server implements HEAD faithfully:

  • some return 405 Method Not Allowed for HEAD even though GET works
  • others omit Content-Length on HEAD that they would send on GET
  • login walls and bot protection may pass a header check but fail on actual download

The GET fallback in the 404 checker handles many HEAD failures. Treat checker output as a strong pre-filter, not a final guarantee every file will save correctly. The redirect checker complements HEAD by flattening 301/302 chains to canonical URLs.

Step 5: build a check-first download habit

  1. paste raw URLs into the 404 checker
  2. copy reachable URLs into a cleaned task
  3. run redirect checks on shortened or moved links
  4. download only the pruned list

Check first, download second—fewer zero-byte files and less time spent on dead links.

Install Bulk Image Downloader Pro when bulk runs should start with cheap header checks instead of full file transfers.

Continue reading: Client Side Image Processing.

Get Bulk Image Downloader Pro on the Chrome Web Store, watch the tutorial video, or visit our YouTube channel for more HTTP HEAD workflow tips.