Filarr Send
End-to-end encrypted file sharing. The server sees nothing.
Send any file to anyone. Encryption happens in your browser, the key is placed in the URL and never reaches our servers.
Short answer
Filarr Send shares any file end-to-end encrypted: AES-256-GCM encryption happens in your browser, and the key stays in the link’s fragment (#), which the browser never sends to the server. No account needed, up to 4 GB in total and 100 files at once; an account raises these limits with your plan.
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Two ways to share
Same crypto, two usage contexts. Pick the one that fits your need.
Filarr Send (web)
filarr.com/send
Anonymous, no account, no install. Drop a file — or a whole batch — in the browser, share the generated URL. Perfect for one-off sends to someone who doesn't have Filarr.
- No account creation
- Up to 4 GB in total, up to 100 files at once
- Max 7-day expiry
- Up to 10 downloads per link
- 3 concurrent active shares per IP
- Sign in and these ceilings follow your plan — same page, nothing to install
Share from Filarr (desktop)
Filarr → right-click → Share via link
From your local vault: right-click any file, configure share options, copy the URL. More control, download history, revocation at any time.
- From your existing encrypted vault
- Up to 50 GB per shared file (Pro)
- Expiry up to 365 days (Pro)
- Manual revocation at any time
- Download history (country + /16 subnet)
- "One download per IP" option
How it works
The full pipeline, from file selection to decryption at the recipient.
- 1
Key generation
Your browser generates a random 32-byte key (K_share). It never leaves your machine in transmissible form — it's base64url-encoded and placed in the URL fragment (#k=…).
- 2
Local encryption
The file is split into 16 MB chunks, each encrypted with AES-256-GCM via WebCrypto. The server never sees the plaintext, never the file name (the manifest is encrypted separately).
- 3
Ciphertext upload
Only ciphertext leaves for our servers (Cloudflare R2). If you enable a password, a random salt is stored server-side — the key is derived with Argon2id, never the password in plain text.
- 4
Decryption at the recipient
When opening the URL, the recipient's browser extracts the key from the fragment (#k=…), downloads the encrypted chunks, and decrypts them locally. The Filarr server only sees opaque requests for opaque ciphertext.
Security, by design
Your files are encrypted in your browser before upload. Our servers only ever store ciphertext — the key is never sent to us.
The key never reaches the server
Placed in the URL fragment (the part after #). RFC 3986 guarantees browsers never transmit the fragment to the server — even our HTTP logs see nothing.
Authenticated AES-256-GCM
NIST standard algorithm. GCM mode protects both confidentiality AND integrity (a modified chunk fails to decrypt). Implemented via the browser's native WebCrypto API.
Password via Argon2id
If you add a password, the real decryption key is derived with Argon2id — a function made deliberately memory-hard, so that testing millions of passwords stays expensive even with dedicated hardware. The server sees neither the password nor the derived key, only a salt. Links created before this change remain readable with their original derivation.
What is public, and what is not
The Filarr desktop client is published on GitHub under BSL 1.1. The worker, the D1 migrations and the Cloudflare infrastructure are not — the Source code page gives the exact scope. Send’s encryption runs in your browser: its code is delivered to you on every visit and stays readable in developer tools, but it is not published as a repository.
Send with or without an account, in detail
| Feature | No account | With an account (Free / Solo / Pro) |
|---|---|---|
| Files per send | 100 | 100 |
| Live volume, in total | 4 GB | 4 GB (Free) / 20 GB (Solo) / 50 GB (Pro) |
| Max expiry | 7 days | 7d (Free) / 14d (Solo) / 30d (Pro) |
| Concurrent active sends | 3 / IP | 5 (Free) / 10 (Solo) / 25 (Pro) |
| Max downloads | 10 | 25 (Free) / 50 (Solo) / 200 (Pro) |
| Optional password | Yes | Yes |
| Manual revocation | Yes | Yes |
| E2EE encryption | AES-256-GCM | AES-256-GCM (same) |
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Try it now. No account required.
Filarr Send runs in your browser. Drop a file, copy the link, share it. That's it.