How DownSwift Works
Every download runs the same seven-step path: expand the link, check the cache, identify the platform, extract the streams, then stream the bytes to your device. Here is each step, in order.
Why the Pipeline Is Built This Way
Each design choice below exists to solve a specific problem, not to look impressive on a diagram.
Short links are resolved first
Links shared from mobile apps are often redirects. DownSwift follows them before doing anything else, so vm.tiktok.com and pin.it links work identically to full URLs.
A 10-minute result cache
Resolving the same link repeatedly is wasteful and looks like abuse to the source platform. Repeat requests inside the window are served from cache.
Explicit platform detection
The hostname decides which extractor runs. An unsupported link is rejected up front with a clear message instead of timing out.
No re-encoding, ever
DownSwift returns the stream the platform already serves. Nothing is transcoded, so quality is never lost and no conversion server is needed.
Stream headers are cached by hash
Some platforms require a matching Referer. Those headers are stored under a one-way hash of the media URL, so the proxy can send them back at download time.
Range-aware streaming
The download proxy forwards HTTP Range requests in 64 KB chunks. That is what makes resuming a large file possible.
Using DownSwift Takes 3 Steps
Copy the post link
In the source app, use Share → Copy Link. On desktop, copy the address bar URL. Short links are fine.
Paste it into the box above
DownSwift detects the platform from the URL. If you want to force one, pick it from the platform tabs.
Pick a quality and save
Preview the media, then choose a resolution or an audio-only stream. The file saves through your browser's normal download flow.
Frequently Asked Questions (FAQ)
Because it is cached. Link results are held for 10 minutes. A second request for the same URL inside that window is answered without contacting the source platform.
Not for the media transfer. Your browser asks DownSwift's proxy for the file, and the proxy fetches it from the platform. The platform sees our server, not your device.
Almost always because the source platform changed something. Platforms rotate their internal APIs and signed URLs regularly. DownSwift never has a stale copy to fall back on, so a changed upstream means a failed download until the extractor is updated.
Usually yes. The download proxy supports HTTP Range requests, so a browser or download manager that supports resuming can continue from where it stopped. Whether it works depends on the browser you use.
No per-user limit is enforced. Very large files may be slower simply because the bytes have to pass through the proxy, but nothing is deliberately capped.
The seven steps, in order
1. You paste a link
The page sends the URL to the API. Nothing is downloaded yet, and no file is created anywhere.
2. The link is expanded
Mobile share sheets rarely give you the canonical URL. A TikTok share gives you something like
vm.tiktok.com/XXXXXXX, which is a redirect. DownSwift follows the redirect chain first,
so every later step works on the real post URL.
3. The result cache is checked
If this exact expanded URL was resolved in the last 10 minutes, the stored result is returned immediately and the source platform is not contacted at all. This keeps repeat use cheap and keeps DownSwift from looking like a scraper.
4. The platform is identified
The hostname decides which extractor runs — TikTok, Instagram, Twitter (X), Facebook, Reddit, Pinterest, Threads, Xiaohongshu or Douyin. If none matches, the request stops here with an explicit "unsupported platform" error. Failing fast is deliberate: a clear error is more useful than a request that hangs.
5. The streams are extracted
The platform-specific extractor asks the source platform for the post's media. What comes back is a list of direct stream URLs — one entry per available resolution for video, plus audio-only streams where the platform offers them. No transcoding happens at any point. DownSwift is a router, not a converter.
6. Stream headers are stashed
Some platforms only serve media when the request carries a matching Referer or
user-agent. Those headers are stored under a SHA-256 hash of the media URL, with a 2-hour lifetime,
so the download proxy can replay them. They are popped out of the response you receive — your
browser never sees them.
7. The bytes are streamed to you
When you press a download button, your browser requests the file from DownSwift's proxy rather than from the platform. The proxy forwards HTTP Range requests, so seeking and resuming work, and it pumps the response back in 64 KB chunks without buffering the whole file in memory.
Why downloads fail
Because DownSwift stores nothing, it has no fallback. Every download is fetched live, so anything that breaks the upstream fetch breaks your download:
- The post was deleted or made private — there is no cached copy to serve.
- The platform changed its internal API — the extractor needs updating.
- The signed media URL expired — most platforms issue time-limited URLs.
- Region blocking — the platform refuses to serve our server's region.
- The post is not actually media — a text-only post has nothing to download.
Privacy, precisely
DownSwift does not require an account, so there is no user record to attach anything to. Media files are never written to disk. The only stored data is the short-lived cache described above: 10 minutes for link results, 2 hours for stream headers. Neither is keyed to a person.
