Compatibility
Which devices and browsers Poftim works with
Both ends need a current browser and nothing else. There is no app to install on either device, no account to create in order to send, and no requirement that the two devices share a manufacturer, an operating system or a network.
Poftim is a web page rather than an installed program, so the question is never whether a particular phone supports it, but whether the browser on that phone does. What follows is what that browser has to be able to do, and where the platforms genuinely differ.
What a browser has to support
Four capabilities, all standard in current browsers
- WebRTC data channels
- The connection itself. This is what lets one browser send bytes to another without an upload step in between.
- Web Crypto
- ECDH on P-256 for key agreement, HKDF to derive session keys, and AES-GCM to encrypt. Without these there is no encrypted session to build.
- JavaScript modules
- The transfer page ships as ES modules. A browser that cannot load them will not get as far as showing a code.
- Blob downloads
- How a received file gets from the page onto the device. This is the capability that varies most between platforms, and it is the usual reason a very large transfer behaves differently on a phone than on a laptop.
Only one of the two devices needs a camera, and only when you pair by scanning. When the devices are apart, or one of them has no camera, use Share connection and send the one-time link instead — how the pairing works covers both routes.
Platforms
What to expect on each one
Poftim is designed for current Safari on iPhone, iPad and Mac, current Chromium browsers — Chrome, Edge, Brave, Opera — on Android, Windows, macOS and Linux, and current Firefox on desktop.
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01
iPhone and iPad
Safari is the engine behind every browser on iOS, so Chrome and Firefox on an iPhone behave the way Safari does. The system camera recognises the code from the ordinary camera view, which is usually the quickest way to join. Long transfers are where iOS differs most: it is aggressive about suspending a page that is not on screen, so keep the transfer visible and the screen awake.
When several files arrive at once, Save all hands the whole set to the system share sheet. That sheet is how iOS saves things: Save to Files puts them in a folder you choose, and Save Images puts photos in your library. iOS offers no way for a web page to write into a folder directly, so the sheet is the route.
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02
Android
Chrome is the usual browser and the one Poftim is built against; other Chromium browsers behave the same way. The built-in camera app scans the code on most devices. As on iOS, putting the browser away during a transfer can suspend the page — the transfer is not designed to survive being backgrounded mid-flight.
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03
Windows, macOS and Linux
A computer is the easier end of a transfer: more memory, no aggressive background suspension, and a real file system to save into. A machine without a webcam still joins perfectly well through a shared connection link, and a laptop showing the code is the normal way to send from a computer to a phone.
Device pairs
Any two of them, in either direction
There is no designated sending device and no designated receiving device. Once two browsers are connected, either side can send, and the same connection carries files both ways until one of them closes it.
- iPhone to Windows PCSupported
- Android phone to MacSupported
- iPhone to AndroidSupported
- Phone to laptop, laptop to phoneSupported
- Two computers, two phones, a tablet and eitherSupported
- Devices on the same Wi-FiUsually faster, never required
- Devices on different networks or in different countriesSupported through the encrypted relay
Sharing a network only changes the route the data takes. When a direct route exists the files go straight across it; when it does not, the encrypted stream passes through a relay that cannot read it. Read how the routing and encryption work.
Known limits
Where it will not work, or will work badly
In-app browsers inside other apps
Opening a link inside a messaging or social app often loads a stripped-down browser view rather than the real browser. These vary widely in what they permit, and some withhold the capabilities above. If a connection will not build from a link somebody messaged you, open that link in your normal browser instead — most in-app browsers have an Open in Safari or Open in Chrome item in their menu.
Old browsers and old operating systems
A browser that predates the capabilities listed above cannot build the connection at all, and Poftim says so rather than half-working. Because the browser on iOS is tied to the system version, an iPhone that can no longer take iOS updates is the most common case.
Private and incognito windows
A transfer itself works in a private window. What does not survive is anything the browser discards when that window closes, so treat it as a one-off: finish the transfer and save the files before closing the window.
Backgrounding a phone mid-transfer
Both mobile platforms may suspend a page that is not on screen, and a suspended page is not sending anything. Keep both pages open and both screens awake for the length of a large transfer.
Networks that block the connection outright
Some corporate, school and guest networks block the traffic a direct browser-to-browser connection needs. Poftim falls back to the encrypted relay in that case, which is slower but usually gets through. A network that blocks the relay as well cannot be worked around from inside a web page.
Saving several files at once
Once more than three files have arrived, the results screen offers a single Save all button. There is no one web standard for saving a set of files to a device, so what that button does depends on the browser — and the line underneath it says which, before you press it.
Chrome, Edge and the other Chromium browsers on a computer ask you to pick a folder once, then write every file into it. A name already in use in that folder gets a number rather than being overwritten. Phones and tablets open the system share sheet with the whole set attached, where Save to Files, or Save Images for photos, puts them away in one step. Firefox on the desktop has neither of those, so it saves the files as separate downloads and may ask once for permission to do that.
The separate-downloads route stops at twenty files. Past that it is a queue of downloads rather than a bulk save, so Poftim does not offer the button at all and says so instead. The folder and share-sheet routes have no such limit — a hundred files is no harder for them than four. The Save button beside each individual file always works, whatever the browser.
How big a file can I send?
Files are streamed in encrypted pieces rather than loaded into memory all at once, so there is no fixed ceiling to quote. What limits a transfer in practice is the two devices, their browsers and the free space on the receiving one. Naming a particular maximum would be a promise nobody has measured.
A formal version-by-version browser and maximum-file test matrix has not yet been completed. Until it is, this page describes what Poftim is built and tested against rather than a certified support list, and no specific maximum file size should be treated as guaranteed.