Pro App File Storage

Pro apps can store and retrieve files through the managed backend. This page explains how to configure file storage and use it from an app.

Stored files vs. source files

An app has two very different kinds of files:

	Source files	Stored files
What they are	The app's own program code	Documents and data used by the app — spreadsheets, text files, configuration, reference lists
Where you find them	Code tab	Backend → Files (Pro apps only)
Who changes them	The App Builder, when you ask for a change to the app	You, by uploading and deleting files — and the app itself while it runs, if allowed

When you talk to the App Builder about a file by its name — for example "show the contents of Product Taxonomy (SMB).txt in a tree" — it means a stored file. The App Builder can list stored files, read them to learn their format, and build the app so it loads them while it runs. It will ask you which kind you mean if the name is ambiguous.

Examples of things you can ask the App Builder:

Add a page that shows the rows of prices.csv grouped by product group.
Read taxonomy.txt and build a collapsible tree from it.
Which stored files does this app use?
Mark settings.json as read-only so the app cannot overwrite it.

Enabling file storage

File storage is available only for Pro apps. To enable it:

Open the app in the App Builder.
Switch to the Backend tab.
Select Files from the left menu.
Turn on Stored Files.

Once enabled, the App Builder can upload files and the app can use them while it runs.

You can also simply ask the App Builder to do it for you, for example:

Enable stored files for this app and let it create new files at runtime.

The App Builder changes both settings itself (the app must already be Pro) and confirms what is now on.

Uploading and downloading files

In the Files section, click Upload File and choose one or more files from your computer. Files are stored privately for this app. Files larger than 5 MB are rejected, and uploads stop once an app reaches 500 files or 100 MB in total.

To get a stored file back, open the row menu (⋯) and choose Download.

The App Builder can also mark a file as read-only. Read-only files cannot be changed or deleted by the app while it runs. They are useful for configuration files, templates, and reference data.

File name rules

File names must use Latin letters, digits, spaces, and basic punctuation. Names with Cyrillic or other non-Latin letters, accented characters, or emoji are rejected — rename the file and upload it again.

Allowed: letters, digits, spaces, and . - _ ( ) [ ] & + , @ ' !
Not allowed: \ / ? # % * : | " < >
The name must not start or end with a space or a dot, must not contain .., and must have an extension
Up to 120 characters

Examples:

Valid:   Product Taxonomy (SMB).txt
Valid:   report_2026-08.csv
Invalid: Product Тaxonomy.txt      (Cyrillic "Т")
Invalid: report:final.csv          (colon)

Limits

Limit	Value
Max files	500
Max file size	5 MB
Max total storage	100 MB

The usage meters at the top of the Files section show the current usage against each limit.

What an app is allowed to do

By default, an app can only read and overwrite files that already exist. It cannot create new files.

To let the app create new files while it runs, turn on Allow app to create files at runtime in the Files section — or ask the App Builder to turn it on.

An app is stopped with a clear message when it tries to do something it is not allowed to do — for example creating a file when runtime creation is off, or changing a read-only file. If you see such a message, adjust the setting in the Files section or ask the App Builder to explain what the app was trying to do.

Showing PDFs inside an app

Apps run in a protected frame, and Chrome does not allow its built-in PDF viewer to run there. If an app tries to show a PDF the usual way, Chrome replaces it with a grey "This page has been blocked by Chrome" box. The file is intact — only the browser's viewer is blocked.

The way around it is to let the app draw the PDF itself, page by page. Ask the App Builder for something like:

Show the attached CV as a real PDF preview inside the dialog, drawn by the app
(not an embedded viewer), with page navigation and a fit-to-width view.

Keep the Open / Download button next to the preview as well: opening the PDF in a new tab always works, because a new tab is not inside the protected frame.

Security

Files are isolated per app. One app cannot access files stored by another app. Files are stored in Operator's managed storage and are not directly reachable from the public internet unless a future public-access feature is enabled.