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-sifter.img.gz. It is 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 and power it on.
5. 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 cable that carries data rather than power only. 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: find the Pi in your router's device list and open https://that-address:8080 instead (for example https://192.168.1.50:8080).
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.

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, so there is no reconfiguration after a restart, and every setting is saved per scanner.

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 (or Raspberry Pi Imager, using Choose OS then Use custom) instead. Etcher takes either the downloaded .img.gz or an already extracted .img such as sortswift-sifter-shrunk.img, so there is no need to download it again. The download is about 2.7 GB and extracts to about 7.6 GB.

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.