Start translating
- Open Settings and find Translation.
- Press Download translation model. Translation is on from the start, so once the model is in, a translation appears under each paragraph in Reading Mode. It goes into the device’s language at first (on a device set to English, nothing is translated until you choose one under Translation language). The paper is never sent to a translation service.
- Choose your language under Translation language and press Download translation model. Then open a paper and press the Translate button in the top bar: a translation appears under each paragraph in Reading Mode. Press it again to put the translations away.
- The first time, Rectoly offers to download the translation model (about 2.5 GB). You download it once; it is kept on the device and stays when the app updates.
- After the download, Rectoly measures how fast this PC translates. With a Vulkan-capable graphics card a paragraph takes a second or two; with only the processor, Rectoly translates just the paragraphs on screen.
- After the download, Rectoly measures how fast this device translates. A fast device also translates the rest of the open paper ahead of you; a slower one translates only the paragraphs on screen. A device that is too slow cannot translate on its own (a paired computer can do it instead).
- To put the translation lines away, press Translate in Reading Mode. Press it again to bring them back.
- If you press Translate before setting it up, the same settings open from there. Translation settings… in the reader's “…” menu opens them too.
- Translation settings… in Reading Mode's ⋮ menu opens the same settings.
Translation is part of the purchase, and it works offline once the model is downloaded. English papers are translated into the languages the app itself speaks and a few more — on a PC and on Android the ones whose quality we have measured, and on the iPad and the Mac the rest are handed to the system translator, with a note saying so.
Translation language
Choose the language to translate into under Settings › Translation › Translation language. With Don’t translate, no translations are shown. The papers translated are the ones in English.
- Translated by this app's own model: Japanese, Chinese (Simplified and Traditional), Korean, German, Spanish, French, Italian, Portuguese (Brazil), Dutch, Danish, Swedish, Norwegian, Polish, Turkish, Indonesian, Vietnamese, Russian, Ukrainian and Arabic.
- Hindi and Thai have not passed our quality check yet, so they are translated on the device by System translation rather than by this app's model. The system downloads the language's data once, the first time. Translations made by the system are not saved to your library.
- Hindi and Thai are in the list but read Not available on this device and cannot be chosen. Only the languages whose quality has been measured are translated by this app's model.
- When you change the language, the paragraphs translated from then on are in the new one.
While you read
- The translation sits under the paragraph, so you can read the original and check yourself against it without leaving the page.
- Rectoly translates ahead of you in the open paper, so the next paragraphs are usually ready before you reach them.
- Translate the rest of the open paper (in Settings) finishes the whole paper while you read.
- Translate the rest of the open paper, under Settings › Translation › Reading ahead, finishes the whole paper while you read. Translate papers that are not open also prepares papers you have not opened yet. Reading ahead rests in Low Power Mode and while the device is hot (the paragraph you are reading is still translated).
- You can also put the translation on the PDF page itself. On a PDF, press the Translate button in the top bar, or choose Show Translated Text in the “…” menu: the layout, columns and figures stay where they were, and Show Original Text switches back. Where two panes fit side by side, Translated pages side by side in the “…” menu opens the translated page beside the original.
- You can also put the translation on the PDF page itself. Under Translate in the PDF toolbar, choose Show Translated Text: the layout, columns and figures stay where they were, and Show Original Text switches back. Where two panes fit side by side, Translated pages side by side opens the translated page beside the original.
- You can also put the translation on the PDF page itself. In the reader’s ⋮ menu, choose Show Translated Text: the layout, columns and figures stay where they were, and Show Original Text switches back. Where two panes fit side by side, Translated pages side by side opens the translated page beside the original.
- On the PDF page, this version leaves paragraphs with math in the original rather than translating them (once per paper, Rectoly says Paragraphs with math are shown in the original).
- To stop, choose Pause translation in the reader's “…” menu. Resume translation carries on from there.
- To discard a paper's translations and start again, choose Retranslate This Paper in the reader's “…” menu.
- To discard a paper's translations and start again, choose Retranslate This Paper. It is in Reading Mode's ⋮ menu and in the Translate menu of the PDF toolbar.
- To discard a paper's translations and start again, choose Retranslate This Paper. It is in Reading Mode's ⋮ menu and in the PDF reader's ⋮ menu.
- Translate Text in Figure, in the menu of a figure or table in Reading Mode, translates the words inside the figure and lists them.
- When the device runs warm or Low Power Mode is on, Rectoly holds back on the paragraphs ahead. If the device gets hot, translation pauses until it cools down (Continue anyway keeps it going).
Translate from a place, retranslate, and your dictionary
On iPad, iPhone and Mac there are four translation tools to use while you read.
- Translate from Here. Select some text and choose Translate from Here: translation starts at that paragraph. Use it when you begin a long paper in the middle. While translation is paused, it resumes from there.
- Translate Selection. Select some text and choose Translate Selection: only what you selected is translated, shown on the spot. Copy Translation copies it. This translation is only shown; it is not saved or shared. When you selected a whole paragraph, Use for the paragraph makes it that paragraph's translation.
- Retranslate This Paragraph. Press and hold a translation line (right-click on a Mac) and choose Retranslate This Paragraph: it is translated again in a different way. Restore Previous Translation goes back if you prefer the first one.
- Translation Dictionary. Select a term in the text, choose Add to Translation Dictionary… and type its translation. Your entry is used in every translation into that language and wins over the term picked for the paper. When you change an entry, only the paragraphs containing the term are translated again.
Terms and Dictionary…, in the reader's “…” menu, shows the terms picked for this paper and everything in your dictionary, to look through and correct. Translation Dictionary under Settings › Translation opens it too.
- The dictionary is stored on this device and is not synced to your other devices. Export… saves it as a file.
- The dictionary works where this app's model (or a paired computer) translates. Languages translated by System translation do not use it.
Translate a selection
- Select some text on the PDF page or in Reading Mode and press Translate in the selection bar, or right-click and choose Translate selection. A card at the top of the page shows what you selected and its translation as it is written; Copy copies it and Close puts it away. The card stays while you move between the PDF page and Reading Mode, and a new selection replaces it. This translation is only shown; it is not saved or shared. If translation is not set up yet, its settings open first.
- Select some text on the PDF page or in Reading Mode and press Translate in the selection bar. A card over the page shows what you selected and its translation as it is written; Copy copies it and Cancel closes the card. This translation is only shown; it is not saved or shared. If translation is not set up yet, its settings open first.
What stays intact
Mathematics, numbers, citation markers like [12] and the terms picked for the paper are masked before translating and checked afterwards. A paragraph that fails those checks shows the original rather than a wrong guess, and a paper keeps the same term for the same thing from the first page to the last.
Check math and numbers in the original
This is how Rectoly avoids showing a formula or a number that might be wrong as if it were right.
- In Reading Mode, a paragraph whose math or numbers could not be confirmed against the original is marked Check the math in the original or Check the numbers in the original. Compare that paragraph with the original.
- On the PDF page, such a paragraph is not translated: the original stays.
- On the PDF page, a paragraph with math is not translated: the original stays. Its translation is in Reading Mode.
Saving translations to your library
- Translations are saved to your own Mendeley library as a file attached to the paper, so your other devices show the same translation without doing the work twice. This is on by default; turn it off with Save translations to my library.
- Rectoly asks before saving translations to your own Zotero storage, and saves nothing without your consent. You can change it later with Save translations to Zotero under Settings › Translation.
- The files are named starting "Rectoly translation (do not delete)" and can be removed in Mendeley or Zotero at any time. Group libraries never get them.
Translating with your own API key
When the device cannot run the model, or you want a larger model to translate, choose Your own API key in Settings › AI: the provider you pick (OpenAI, Anthropic, Google and others) translates instead.
- The paragraphs to translate go from the device straight to the provider. Before you start, Rectoly shows what is sent and asks for your agreement.
- The first time a paper is translated, you see an estimate of how much will be sent and confirm it. Translating papers ahead that you have not opened stops.
- For the set-up and what is sent, see AI settings and your own API key.
Translate for your phone and tablet
This computer can translate on behalf of an iPad or Android device on the same network:
- In Settings, open Phone & tablet and turn on Translate for my phone and tablet.
- You need the translation model downloaded and the speed measured first.
- Download the translation model under Settings › Translation first. This setting is in the Mac version downloaded from rectoly.com; the Mac version from the App Store does not have it.
- The system may ask whether to let Rectoly use the network. Allow it. Only devices you have paired, on the same Wi‑Fi, can use it.
- In the Windows prompt, choose Allow access.
- In the macOS prompt, choose Allow.
- Press Start pairing and scan the QR code with Rectoly on the device (or press Show the code and type the six digits there).
- On Linux, a firewall (ufw or firewalld) needs one TCP port and UDP 5353 (mDNS) allowed. Rectoly says what to allow when you turn the switch on.
- From then on the device sends paragraphs to the computer, encrypted for that pair of machines; the computer translates and sends them back. Nothing leaves your network.
- On a Mac, closing the window does not quit Rectoly: it stays in the Dock and keeps listening. Quit it with ⌘Q to stop.
Let your PC translate
Rectoly on a computer on the same network can translate for this device — without the translation model being downloaded here, and even on a device with less than 8 GB of memory.
- The computer runs Rectoly for Windows or Linux. It also helps a device the speed check found too slow.
- The computer runs Rectoly for Windows or Linux, or the Mac version downloaded from rectoly.com.
- On the computer, open Settings › Phone & tablet, turn on Translate for my phone and tablet and press Start pairing.
- On this device, open Settings › Translation › Translate on my PC and use Scan the QR code on the computer’s QR code. On a device that cannot scan, pick the computer in the list below and type the six digits it shows.
- From then on the device sends paragraphs to the computer, encrypted for that pair of machines, and the computer translates and sends them back. If the computer cannot answer, this device translates the paragraph itself — when it has the model.
Requests while you are away
With Take requests on, this computer translates the paragraphs not yet translated in papers you read on your phone or tablet, and saves the translations to your library — only papers in your personal library that are downloaded on this computer, and only while it is plugged in. Rectoly checks Rectoly's server for a signal every 30 seconds; only signals pass through the server, never the paper or its translations.
- Rectoly stays in the notification area when you close its window, and keeps taking requests.
- Sign in with the same account as on your phone or tablet, and turn on saving translations to your library under Settings › Translation. No requests are taken while Rectoly is quit or the Mac is asleep; the next time it runs, it starts with the requests that arrived meanwhile.
Taking requests works on Linux too. A desktop with a notification area behaves like Windows; on one without it (plain GNOME, for example), closing the window stops Rectoly, so keep the window open — the app says so when it applies. On neither system does Rectoly start itself at login.
A second PC at home can turn on Wake my translating PC when a request comes to wake the translating PC from sleep. The sleeping PC's network adapter needs "Wake on Magic Packet" turned on, and in practice a cable connection to the router — Wi‑Fi rarely wakes it.
Ask your PC from anywhere
With Ask my PC from anywhere on (Settings › Translation), closing a paper asks your PC at home to translate the paragraphs not yet translated. The PC saves the translations to your library, and the next sync brings them to this device. Only signals pass through Rectoly’s server, never the paper or its translations.
- The PC has to be on and signed in, with Take requests turned on there. It works on papers in My Library that are downloaded on that PC.
- Check whether my PC can be reached tells you whether a request can go now. When it cannot, Rectoly says why and what you can do instead.
- A request is not lost when the PC is off: it waits beside the paper, and the PC picks it up the next time it runs.
When the device cannot find the computer
- The same Wi‑Fi name. Join the device to the Wi‑Fi with the same name as the one the computer is on. A router that gives its 2.4 GHz and 5 GHz bands different names treats them as separate networks, and pairing can fail even though the computer's name is in the list.
- The firewall question. If you dismissed the Windows firewall prompt without choosing Allow access, open Windows Security → Firewall & network protection → Allow an app through firewall, and allow Rectoly.
- Network type. Windows treats networks as Public or Private. Rectoly listens on the network you turned the switch on for; if the PC later joins a different network, Settings shows "This is not the network you turned this on for" with a Use this network button.
- A different network. When the Mac joins a network other than the one you turned the switch on for, Settings says so. Press Use this network.
- Guest Wi‑Fi and university networks often block devices from talking to each other. Pairing then fails even though both machines are online; a home network or a private hotspot works.
- VPNs and virtual adapters (a VPN tunnel, WSL, a virtual machine) can swallow the connection. If the device cannot find the computer, try turning the VPN off, or pick the real Wi‑Fi adapter's network in Settings.
- Both editions on one computer: each edition pairs separately — pair with the one you read in.
What you need
- A 64-bit x86 processor with AVX2 and 8 GB of memory. A Vulkan-capable graphics card makes translation quick; without one, only the paragraphs on screen are translated, and on a very slow machine translation may be unavailable.
- To translate on the device itself, roughly 8 GB of memory or more. Speed varies from device to device and is measured after the download. A device short of memory or too slow still reads translated papers through a paired computer.
- To translate on the device itself, an iPad, iPhone or Mac with 8 GB of memory or more. A device with less says This device cannot run on-device translation. It can still read translated papers through a paired computer or with your own API key.
- About 3 GB of free space for the model and its working files.