File Sharing

Atrium makes it easy to deliver files to clients without relying on email attachments or external drives. Files are uploaded to a project from the dashboard and become available for clients to download from the portal.

Uploading files

Only owners and admins can upload files from the dashboard.

Open a project

Navigate to Projects and open the project you want to attach a file to.

Go to the Files tab

Click the Files tab in the main content area.

Upload

Click Upload File and select a file from your computer. The file uploads immediately and appears in the file list.

Uploaded files are organized per project — a file belongs to exactly one project and is only visible to clients assigned to that project.

The default maximum file size is 50 MB. Your administrator can raise or lower this limit by setting the MAX_FILE_SIZE_MB environment variable. The upload form enforces the configured limit and shows an error if the file is too large.

Client uploads

Clients can also upload files from the Files tab in the portal. Client uploads follow the same per-project access rules — a client can only upload to projects they are assigned to.

Downloading files

Clients see all files attached to their projects in the Files tab of the portal. Each file shows the filename and file size, with a Download button that streams the file directly to their browser. Team members can download any file from the Files tab in the dashboard.

File size limits

Setting	Default	How to change
Maximum file size	50 MB	Set `MAX_FILE_SIZE_MB` in your environment

The limit applies to all file uploads, including files attached to updates and uploaded invoices. The server rejects any upload that exceeds the configured limit before storing the file.

Storage backends

Atrium abstracts file storage behind a configurable provider. You can store files on the local filesystem (the default) or in a cloud object store. Configure the backend using environment variables before starting the server — changing the backend after you already have uploaded files requires manually migrating existing data.

Local disk
Amazon S3
MinIO
Cloudflare R2

Files are stored on the server’s local filesystem. This is the default and requires no additional configuration. Suitable for single-server deployments where the disk is persistent.

STORAGE_PROVIDER=local
UPLOAD_DIR=./uploads   # optional, defaults to ./uploads

Files are stored in an S3 bucket. Use this for production deployments where you want object storage durability and CDN support.

STORAGE_PROVIDER=s3
S3_REGION=us-east-1
S3_ACCESS_KEY=your-access-key
S3_SECRET_KEY=your-secret-key
S3_BUCKET=your-bucket-name

Files are stored in a self-hosted MinIO instance. MinIO is S3-compatible, making it a good choice if you want object storage without a dependency on AWS.

STORAGE_PROVIDER=minio
S3_ENDPOINT=https://your-minio-host
S3_REGION=us-east-1
S3_ACCESS_KEY=your-minio-access-key
S3_SECRET_KEY=your-minio-secret-key
S3_BUCKET=your-bucket-name

Files are stored in a Cloudflare R2 bucket. R2 is S3-compatible and has no egress fees, making it an economical choice for high-download workloads.

STORAGE_PROVIDER=r2
S3_ENDPOINT=https://<account-id>.r2.cloudflarestorage.com
S3_REGION=auto
S3_ACCESS_KEY=your-r2-access-key
S3_SECRET_KEY=your-r2-secret-key
S3_BUCKET=your-bucket-name

Executable file extensions (.exe, .sh, .bat, and others) are blocked regardless of the storage backend. The server returns an error if you attempt to upload a blocked file type.

For a complete list of environment variables and deployment guidance, see the Configuration reference.

Get Started

Core Features

Branding

Payments

Configuration

Uploading files

Client uploads

Downloading files

File size limits

Storage backends

​Uploading files

​Client uploads

​Downloading files

​File size limits

​Storage backends

Uploading files

Client uploads

Downloading files

File size limits

Storage backends