What Sync.com does well
Sync.com is a genuinely good product, and it is worth saying so plainly. It is zero-knowledge and end-to-end encrypted by default on every plan, including the free tier: files are encrypted on your device, and Sync states it cannot read your content. That zero-knowledge property extends to file data, metadata, the web panel, and sharing; share links get the same protection when its "Enhanced privacy" option is on, and otherwise rely on TLS. This is the right architecture, and Sync has built its whole product around it since 2011.
It also carries credibility a newer product cannot. Sync is a Canadian company that stores data on Canadian soil, and — importantly — it has a real, independent third-party audit: SOC 1 / SOC 2 / SOC 3 examinations by a named CPA firm, with a publicly downloadable SOC 3 report, plus HIPAA with a BAA on its Pro plans (Pro Solo 5 TB, Professional, Unlimited and Pro Teams). If you want an established, externally audited, zero-knowledge product with a strong track record, Sync is a strong default.
The rest of this page is about the specific tradeoffs where ShieldFive fits better — and, just as honestly, where Sync is ahead.
Why people look for an alternative
People who already trust Sync still come looking, usually for one of a few concrete reasons:
- Post-quantum protection today, not classical-only. Sync's encryption is entirely classical (AES-256, with no post-quantum work described). It is excellent against today's attackers, but it offers no defense against "harvest now, decrypt later" — an adversary storing ciphertext now to decrypt once a quantum computer can break today's public-key algorithms.
- An open, checkable crypto core. Sync's apps and crypto implementation are fully closed source. You have to trust its published documentation (the detailed encryption white paper dates from 2015) and the audit; you cannot read the code that encrypts your files.
- EU jurisdiction and data residency. Sync is Canadian, and Canada is a Five Eyes member. Some buyers specifically need EU data residency and GDPR jurisdiction.
ShieldFive: implementation and limits
ShieldFive encrypts files on the device before upload. Your password never reaches our servers: the browser turns it into a separate login value with Argon2id and sends only that, and the key that opens the vault is derived separately and stays on the device. The app code is delivered by ShieldFive, so the client you are served remains part of the trust boundary; client-side encryption does not mean that ShieldFive is technically unable to decrypt files.
Web uploads default to ML-KEM-1024/XChaCha20-Poly1305, with an AES-256-GCM fallback. Android also defaults to the hybrid format, with the same AES-256-GCM fallback, and reads both formats. This is not post-quantum hybrid encryption on every client or every upload.
Encrypted data is stored in the EU. The crypto core is open under Apache-2.0; the applications are closed-source and no external security audit has been completed. Review the security model and current plans before choosing.
ShieldFive vs Sync.com at a glance
| Capability | ShieldFive | Sync.com |
|---|---|---|
| Post-quantum on stored files | Hybrid default on web and Android, AES-GCM fallback | No — classical (AES-256) only |
| Zero-knowledge / end-to-end | Client-side; client-code trust applies | Yes, by default |
| Open-source crypto | Yes — @shieldfive/crypto, Apache-2.0 | No — fully closed source |
| External third-party audit | No (internal review published) | Yes — SOC 1/2/3, public SOC 3 report |
| HIPAA / BAA | No | Yes — Pro plans only |
| Jurisdiction | EU data residency | Canada (data stored in Canada) |
| Free tier | 5 GB, no card | 5 GB, no card |
Where Sync.com is ahead, honestly
Two of Sync's advantages are real and matter, and we would rather say so than imply a parity that has not been earned:
- Sync has an external audit; ShieldFive does not. Sync's SOC 1/2/3 examinations by an independent CPA firm, and its HIPAA/BAA support on Pro plans, are certifications ShieldFive simply does not have yet. ShieldFive has published an internal security review, but that is not the same as an external audit. If formal, third-party certification is a hard requirement for you today, that is a clear point in Sync's favour.
- Sync is mature and proven. It has operated since 2011, is profitable, has a large paying user base, and ships full-featured apps across every platform. ShieldFive is newer and smaller.
The trust boundary is still a difference: ShieldFive’s sign-in password never reaches its servers, but the app code is delivered by ShieldFive, so its client-side encryption should not be presented as the same provider-inaccessible guarantee.
Which one fits you
Choose Sync.com if an external SOC/HIPAA audit and a decade-long track record are non-negotiable today, and you are comfortable with classical, closed-source encryption under Canadian jurisdiction.
Choose ShieldFive only if its client-code trust boundary, client-specific encryption formats and current assurance limits meet your requirements. Test upload, viewing, sharing and recovery with disposable files before moving important data.
Comparison reflects each vendor's public documentation as of 2026-09-22. Check current pricing and certifications on each vendor's site, since both change over time.
Try it
Start with disposable files and review the security model, including client-code trust and web/Android differences. See current plans.