Relaaay vs Resilio Sync: Which One Should You Trust With Deletions?
Resilio Sync is a powerful peer-to-peer folder mirroring tool, but it is built around exact directory mirroring — delete a file on your phone to free up space, and Resilio deletes the source file on your desktop too. It also struggles to write into iOS's Photos library in the background, the same sandboxing limit that affects Syncthing. Relaaay lets you turn off deletion syncing per device and is built for reliable delivery on iOS.
Resilio Sync descends from BitTorrent's peer-to-peer transfer technology, and it shows — it is fast, decentralized, and capable of handling enormous folders without a central server. Among technical users and IT admins managing large personal or team archives, it has a loyal following.
It is also built on an assumption that quietly turns dangerous the moment a phone is one of the synced devices: every copy of the folder is supposed to be identical, forever.
What Resilio Sync does well
Resilio syncs directly between devices with no cloud storage account required, using efficient block-level transfer that scales well to large media libraries. Setup, while more technical than a consumer app, gives you fine-grained control: per-folder permissions, selective sync, and read-only mirrors for archival devices.
For a pair of desktops, a home server, or a technical user managing terabytes of files across machines they control, it is a genuinely capable tool.
Where it breaks down for everyday device sync
Two structural issues make Resilio a poor fit once a phone — and a normal, non-technical workflow — enters the picture.
- Deletions mirror by default. Resilio's core design goal is exact directory replication: every synced device should hold the same files. That means deleting a video from your phone to free up storage deletes the same file from your desktop archive, even if the desktop copy was your only backup.
- iOS fights it the same way it fights Syncthing. Apple's sandbox suspends background processes, and Resilio needs a continuous one to detect changes and exchange data. The practical result is the same stale-until-reopened behavior that makes P2P sync unreliable on iPhone.
- It's built for people who want to configure it. Sync keys, per-folder permissions, and manual device linking are strengths for an IT admin and friction for someone who just wants their camera roll to show up on their laptop.
How they actually compare
| Resilio Sync | Relaaay | |
|---|---|---|
| Sync model | Peer-to-peer exact mirroring | Fan-out delivery to every group member |
| Deleting a file on one device | Deletes it everywhere by default | Optional — deletion sync is a per-device choice |
| iOS background reliability | Unreliable — suspended by sandbox | Yes — built for iOS delivery |
| Setup | Sync keys, per-folder permissions | Link a folder, join the group |
| Target user | Technical users, IT admins, large archives | Anyone moving files between their own devices |
| Cloud fallback when devices aren't both online | Limited | Yes — relay routing, then Cloudflare R2 |
| Cost | Free personal tier, paid business tiers | Free / Creator $9/mo / Agency $49/mo |
Resilio is the right tool if you want exact mirrors across machines you administer and you understand the tradeoffs. It is the wrong tool if a phone is involved and you don't want a low-storage day on your phone to quietly erase your desktop archive.
What fills the gap
Relaaay separates "sync new files" from "sync deletions" on purpose. A Folder Group has a group-level switch for whether deletions propagate at all, and every device can independently opt out of receiving them — so your desktop can stay the permanent archive while your phone stays disposable, exactly the shape most real workflows actually need.
On iOS, Relaaay doesn't depend on an app staying awake in the background. It delivers files in a way iOS supports, so the folder stays current without you holding anything open.
Mirroring is a feature until the day it deletes something you needed. Sync should ask before it assumes.
If you're managing archives across machines you control and you're comfortable configuring the tradeoffs, Resilio remains a solid choice. If you want a phone in the mix without gambling your desktop copy on a low-storage afternoon, that's the problem Relaaay solves.