The Office editor app

The Office editor app, filex-office-editor, is how filex edits Word, Excel and PowerPoint documents and their kin - and, from its 0.4.0 (for filex 0.57), how filex draws their thumbnails and converts them on the server. It needs no ONLYOFFICE Document Server: an installation that has one can delete its container (Moving from a Document Server).

It is an app like any other: an administrator installs it, reviews what it asks for, and approves every update. It is AGPL-3.0, based on ONLYOFFICE Docs by Ascensio System SIA, and its source, build and measurements are in its repository. This page says what it does in filex; ONLYOFFICE.md is the reference for office editing as a whole, with or without a Document Server.

At a glance

	Where it runs	What it does
The editor	in the person's browser, in a sandboxed frame filex draws	opens 45 kinds of office documents, edits them alone or with others, saves a new version, prints, downloads in other formats
The office engine (`engine.zip`, 0.4.0)	on the filex server, in a process of its own, with no network	draws office thumbnails and makes the office conversions apps ask for (the Convert app, MCP's `file_convert`)

Both come from ONLYOFFICE's own code: the editor's files from the official Document Server image, and x2t, ONLYOFFICE's converter, compiled to WebAssembly by the project. On the server the editor's own page layout (sdkjs) runs in a JavaScript engine compiled to WebAssembly too, so a thumbnail or a PDF is laid out the way the editor lays it out.

What it does

In the browser

Opens 45 kinds in place of the preview - Word: .docx, .docm, .dotx, .dotm, .doc, .dot, .odt, .ott, .fodt, .rtf, .wps, .wpt, .stw, .sxw, .mht, .mhtml; Excel: .xlsx, .xlsm, .xltx, .xltm, .xls, .xlt, .xlsb, .ods, .ots, .fods, .csv, .et, .ett, .sxc; PowerPoint: .pptx, .pptm, .potx, .potm, .ppsx, .ppsm, .ppt, .pot, .pps, .odp, .otp, .fodp, .dps, .dpt, .sxi. Before 0.4.0 it opened six of them (.docx, .xlsx, .pptx, .odt, .ods, .odp). A person who may only read a file opens it to read.
Saves a new version. Save (the editor's button, Ctrl+S, or filex's Save) writes the file in its own format as a new version; while there are changes it also saves every ten minutes, and filex asks before a person leaves unsaved work.
A format it cannot write is saved beside the file. .doc, .xls, .ppt, their older templates, the WPS and StarOffice kinds, .mht and the flat OpenDocument kinds are saved as .docx, .xlsx or .pptx next to the original, which stays as it was (report.doc → report.docx, then report (2).docx); the editor says where the save went (A save in another format).
A conflict copy, never a lost change. A file somebody changed after it was opened keeps their version; the save goes beside it as <name>.filex-conflict-<time>.<ext> (When the document changes while it is open).
CSV in its own dialect. A .csv opens with its own delimiter and encoding and is saved the same way - delimiter, byte order mark and line ends as the file had them, the cells nobody changed byte for byte (CSV files). Download as CSV offers every code page of the editor's list.
Password-protected documents open after the editor asks for the password, and stay protected when they are saved. The password never leaves the person's browser.
Spelling and hyphenation in filex's interface languages (English, Turkish, German, Spanish, French, Arabic) out of the box; an administrator adds any of 43 more with one click, each file checked against the release's SHA-256 (Dictionaries for the office editor).
Macros run after the editor asks whether they should, as a Document Server runs them.
Editing together. Several people edit one document at once through filex's own relay; a person who may only read follows the changes live (Editing together). Comments and tracked changes carry each person's name.
Encrypted folders. A document in an encrypted folder or vault the person has unlocked opens too: the browser decrypts it for the editor and encrypts the save before it leaves, so the server sees only encrypted data (E2E-OFFICE.md).
Print and Download as. Through filex: DOCX, ODT, RTF, TXT, XLSX, ODS, CSV, PPTX, ODP, their templates, PDF and PDF/A, made in the browser from the editor's own pages.
New document gets six rows: a document, a spreadsheet and a presentation, as OOXML and as OpenDocument (Creating new documents).
The editor's language is the person's, or the one an administrator fixed for everybody (The editor's language); zoom, units and the other editor settings are kept between openings.
On a phone a document opens in ONLYOFFICE's phone view to read, with Edit.

On the server: the office engine

From 0.4.0 the app's release carries engine.zip: x2t built for WASI, layout-host.wasm (sdkjs in QuickJS) and the layout's scripts, each named in the app's manifest by its SHA-256 (engines.office; the install review lists it as office-engine). filex runs it in a process of its own - filex office-engine, a hidden command of its own binary - and never links it into the server (The office engine without a Document Server).

Office thumbnails. The picture of the first page, 320 pixels on its long side, at a Document Server's sizes: a letter-sized document 247 x 320, a spreadsheet 320 x 320 in filex's sheet layout, a 4:3 presentation 320 x 240 (Thumbnails).
Office conversions for apps. The Convert app's office targets (Word, Excel, PowerPoint and OpenDocument to each other, PDF and PDF/A, HTML, EPUB) and MCP's file_convert, with no change to the apps (Office conversions for apps).
No network. The engine sees the job's own directory and the app's package; a picture a document only links to is left out, never fetched.
Prepared once. After an install, an update, or a new filex, the engine is compiled in the background - a minute or two on a machine with 8 to 12 cores, up to five minutes on a slower one - and later processes load it from the cache in <data dir>/office-engine/ in about a second. Admin → Plugins → Default apps → Office engine says Being prepared, then Ready (Being prepared).
Memory. Each module is capped by FILEX_OFFICE_ENGINE_MAX_MB (2048 by default); an engine process stays far below it for ordinary documents (Memory).

Install it

An administrator, once; filex never installs it by itself.

From a store. On filex Apps press Install on Office editor and give your filex's address: the install review opens on your filex (Installing from a store).
From GitHub. Admin → Plugins → Apps → Install an app → GitHub repository: BRF-Tech/filex-office-editor, tag v0.4.0 (From GitHub, step by step).
From its files, on a server that cannot reach GitHub: download filex-app.json, ui.zip and engine.zip from the release, then Install an app → Upload files with the manifest, Interface ui.zip and Office engine engine.zip (no module).

Read the permission review and press Install. The review lists the file it was opened with (files:read, files:write), the documents of encrypted folders (files:e2e-plaintext), editing together (files:co-edit), what its interface may do (its own package, frames of it, blob: addresses, the script exceptions ONLYOFFICE's editor and x2t need, Download as and Print), the 45 kinds it opens and the six New document rows - and office-engine, the engine filex runs on the server.

Which release for which filex:

filex	Office editor	What it adds
0.57 or later	0.4.0	the office engine (thumbnails, conversions), 45 kinds, CSV, password-protected documents, dictionaries, macros, conflict copies, OpenDocument rows in New document
0.56	0.3.1 (0.2.0, 0.3.0)	encrypted folders (0.2.0), editing together (0.3.0)
0.55	0.1.1	the editor, one person, six kinds

A filex refuses the manifests made for a later filex, so the store and the review only offer what fits.

Update it

Nothing updates by itself. When a new release is out, Admin → Plugins → Apps marks the app Needs approval; Review update shows the permissions the new version adds and the release notes. From 0.3.1 to 0.4.0 it adds office-engine, the 39 new kinds and the three OpenDocument rows, and asks, kind by kind, where the app goes in File types: first, after the ones that open the kind now, or off. ⚠ A kind another editor already opens - a .csv a Document Server opens - keeps that editor first unless you choose First; Default apps changes it later. After the update the engine is prepared again (Being prepared, then Ready); while it is, a connected Document Server takes its jobs.

Without a Document Server

There is nothing to configure: no address, no secret, no callback. Install the app; once its engine is Ready, office documents get their thumbnails and the Convert app its office targets. An installation that never had a Document Server needs nothing else.

Moving from a Document Server

An installation that used a Document Server for editing, thumbnails and conversions can move every one of them to the app and stop the container:

Install or update the app to 0.4.0 and wait until Default apps → Office engine says Ready for it. The Document Server keeps working meanwhile: by default the app's engine is asked first, the Document Server after it (The engine and a Document Server).
Put the app first under Default apps for every kind the Document Server opened, .csv included. A rule that names the app first keeps it first even if a Document Server is connected again later.
Remove the Document Server from the environment: FILEX_ONLYOFFICE_URL, FILEX_ONLYOFFICE_JWT and FILEX_ONLYOFFICE_FRAME_ORIGIN (or the external_services.onlyoffice block of config.yaml), and restart filex.
⚠ Switch it off under Admin → Settings → External services too, and clear its address and secret. The environment only gives the first value; the stored ONLYOFFICE row then belongs to the admin page (Point filex at it). Removing the variables leaves that row as it was, and filex goes on sending the editor, the thumbnails and the conversions to the Document Server. Through the API: PATCH /api/admin/external/onlyoffice with {"enabled": false, "url": "", "secret": ""}.
Check it. GET /api/capabilities says "onlyoffice_url": "" and external.onlyoffice.state disabled; under Default apps → Office engine the app's engine is Ready and the Document Server is no longer connected. Open an office document, save it, and look at the thumbnail of one you upload.
Stop the Document Server, and remove what only it used: the proxy's site for its address, the /filex-frame/* route to filex on it, its secret.

The thumbnails the Document Server drew stay valid: both are the same ONLYOFFICE drawer, so nothing is drawn again because the back end changed.

Known limits

Fonts. The app brings metric-compatible free fonts (Liberation, Carlito, Caladea) in place of the Microsoft fonts ONLYOFFICE's image installs: lines break in the same places, the glyphs look different. Fonts added to a Document Server are not used; if they matter, keep a Document Server and put it first under Office engine (Where it differs from a Document Server).
Speed. The engine is slower than a Document Server's native x2t: a conversion takes about 1.4 to 3 times as long, and a document's layout (a thumbnail, a PDF) 2 to 20 seconds.
Formats it does not write. No FB2. Download as in the editor has no HTML or EPUB; the Convert app makes both through the engine.
Linked pictures - a picture or a style sheet a document names on another server - are left out, in the editor, the thumbnails and the conversions alike.
ONLYOFFICE plugins are off: most of them need the network, and none is in the package.
Large spreadsheets need memory: a 200,000-row CSV took 2.6 GiB in the engine, above the default cap - raise FILEX_OFFICE_ENGINE_MAX_MB for such files.

The Office editor app ​

At a glance ​

What it does ​

In the browser ​

On the server: the office engine ​

Install it ​

Update it ​

Without a Document Server ​

Moving from a Document Server ​

Known limits ​

See also ​