Building a Simple Sifter takes a Raspberry Pi 4 or 5 (the 5 gives the best performance), a USB-C power supply, an SD card, and a Fujitsu or Ricoh document scanner. The fi-8170 is the model the Sifter is tuned for. SortSwift does not sell any of the parts and the Sifter image is free.

1. Download the Sifter image from https://sortswift.nyc3.cdn.digitaloceanspaces.com/sifter/sortswift-sifter64.img.gz. It is the 64-bit image, and an SD card image for the Pi, not a Windows installer, so it is never opened on your computer.
2. Download Balena Etcher from https://etcher.balena.io/
3. In Etcher click Flash from file and pick the image, then Select target and pick your SD card, then Flash. When it moves on to Validating you can hit Skip.
4. Put the SD card in the Pi. If you can, plug an Ethernet cable from the Pi into your router now, then power the Pi on.
5. Connect the Pi to your network. With the Ethernet cable in (recommended, it has lower latency and faster uploads than Wi-Fi), the Pi joins your network by itself and the Sifter starts, so there is no Wi-Fi step and the simplesifter network does not appear: go on to step 6. Without a cable, from a laptop or phone, join the Wi-Fi network called simplesifter followed by a number (for example simplesifter-210), password sortswift. It has no internet by design, so ignore a "No internet" label and stay connected. Open http://10.41.0.1/ and follow the prompts to put the Pi onto your own network.
6. Plug the scanner straight into the Pi, with no hub in between, into one of the blue USB 3 ports, using a SuperSpeed USB 3.0 or better data cable (not a power only cable). The scanner always connects by USB, never through its own network port. Power both on.
7. Open https://simplesifter.local:8080. It warns about the certificate because the Pi signs its own, so click Advanced and then Proceed. That warning has to be cleared once or the web app cannot talk to the Pi. Then log in with your SortSwift account, or with a staff login whose staff account has the Simple Sifter permission. If it says "This site can't be reached", your network is not resolving the simplesifter.local name and the warning has not appeared yet: open https://that-address:8080 instead (for example https://192.168.1.50:8080), and clear the same certificate warning there. To find that address, open your router's app or its admin page (the address and login are usually printed on a sticker on the router) and look in its list of connected devices for one named simplesifter. Some routers list it as Raspberry Pi instead. A Pi with both a cable and WiFi is listed twice, and either address works.
8. Open the scanner page in SortSwift and set the left panel toggle to Sifter instead of File Upload. If you reached the Pi by its IP address, type that same address into the Sifter Hostname box on that page. From Simple Sifter 11.6.41, once you have signed in on the Sifter, it tells your SortSwift account its address on your network. From 11.6.42 a new Sifter does this before anyone has signed in on it too, so it also helps during first setup. When the scanner page cannot reach the Sifter, it then shows "Your Sifter reported" (or, during first setup, "A Sifter on your network reported") with that address and a Use it button, which puts the address in the Sifter Hostname box for you. The page only shows this while it is on the same internet connection as the Sifter.

You can run up to four scanners from one Pi, one on the free plan and up to four on a paid scanning plan. The image updates itself after that. It installs a new version whenever it starts, and from Simple Sifter 11.6.1 it also installs one by itself once no scanner is running and nothing has been scanned for 30 minutes, then restarts once. An update never starts while you are scanning, and from 11.6.35 not while you are reviewing cards either: approving, editing, deleting or sending a card restarts the 30 minutes. There is no reconfiguration after an update or a restart, and every setting is saved per scanner.

Older Sifters: every Sifter update now comes out for the 64-bit image only. A Sifter flashed with the earlier 32-bit image (its page shows a version lower than 11.5.2) keeps working, but it gets no more updates until it is reflashed with the 64-bit image. Flashing erases the SD card and everything the Sifter keeps on it: each scanner's settings (Quality, crop settings and stop rules), the active batch and every saved batch, the label settings and templates, and the store logo. The Pi and the scanner stay as they are. Before you flash, finish and send any batch you still need. To keep your saved batches, click Export All under Saved Batches on the Sifter's page and keep the file it downloads. Scanner settings cannot be exported, so note down any you want to set up the same way. Then flash the SD card with the 64-bit image as above, plug in the Ethernet cable or join the simplesifter Wi-Fi again, clear the certificate warning again and log in. To bring the saved batches back, click Import under Saved Batches and pick the file you downloaded.

Do not open, mount or double click the image in Windows. If you do, Windows shows "Couldn't Mount File. The disc image file is corrupted." That does not mean the download is damaged. File Explorer can only open ISO style disc images, and the Sifter file is a Raspberry Pi SD card layout, so Windows cannot read it even when every byte is intact. Close the message and flash the file with Balena Etcher instead. Etcher takes either the downloaded .img.gz or an already extracted .img, so there is no need to download it again. The download is about 2.0 GB and extracts to about 7.3 GB.

If you flash with Raspberry Pi Imager instead of Etcher, use Choose OS then Use custom, and when Imager offers OS customisation choose No. Customising replaces the user the Sifter's own start-up steps run as, and the Sifter does not start properly.

Do not install PaperStream on the Pi. The Pi drives the scanner through SANE, the Linux driver stack, and the image already has everything it needs. PaperStream is only for the separate route where the scanner is plugged into a Windows laptop.

Two computer settings are also needed to reach the Sifter. Your computer's network must be set to Private, not Public: on Windows open Settings, then Network and internet, click the WiFi or Ethernet connection you are on, and set Network profile type to Private network. Your browser must also be allowed to access local devices: when Chrome asks, choose Allow, or click the icon to the left of the address bar on the SortSwift scanner page, open Site settings, and set Local network access to Allow.