Holdfast vs Safe4: honest comparison

01The short verdict

All Safe4 facts on this page were taken from Safe4's own published material and verified in May 2026. Where a detail could not be confirmed, it was left out rather than guessed. If anything has moved since, we would rather know than not. Drop us a line.

Safe4 is a mature, well-credentialed custodial document vault. It has been operating since 2010, is Cyber Essentials certified, has been penetration tested under the GCHQ-administered IT CHECK scheme, hosts on Rackspace UK infrastructure with ISO 27001 certification, holds an A+ TLS rating, and partners with the Society of Will Writers. It is a filing cabinet that a firm manages for clients, where access is granted in advance by inviting an executor or a family member.

Holdfast is a zero-knowledge vault with an automated dead man's switch. The contents are encrypted in the browser and nobody at Holdfast holds the key. When a user stops checking in, Holdfast delivers the encrypted vault to nominated recipients on its own, after a documented grace and escalation period. Safe4 is a filing cabinet with permissions granted in advance. Holdfast is a delivery mechanism that fires without anyone having to act.

Holdfast is operated under UK GDPR, which the EU recognises as providing an equivalent level of protection under its adequacy decision. Users worldwide are welcome, and data is processed to UK and EU standards regardless of where the user is based. The Holdfast Firm tier is built for professional firms offering digital legacy planning to clients as part of their service: UK solicitors and IFAs, and their international counterparts in legal and financial services.

02Encryption and threat model

Both encrypt at rest with AES-256. The decisive difference is who holds the key, and therefore who can read your files.

Safe4 encrypts uploaded files with AES-256, but it manages the keys on the server. This is a custodial model: the operator can, in principle, access file contents. The clearest tell is Safe4's own note that in-file text search is not supported, because the indexes it would require cannot themselves be encrypted. That is an honest disclosure, and it is the natural consequence of a design where the service holds the keys.

Holdfast is zero-knowledge. Files are encrypted client-side with AES-256-GCM, and the key is derived from a passphrase you choose using Argon2id, a memory-hard function run at OWASP minimum parameters against a per-user salt. The passphrase never leaves your browser and is never transmitted or stored, so the operator cannot read vault contents. The encryption module is open source at github.com/Nexus-sectech/holdfast-crypto and is loaded with Subresource Integrity, so the browser refuses to run it if the file has been altered.

The trade-off cuts both ways, and it is worth being even-handed about it. A custodial model like Safe4's allows server-side search, operator-assisted recovery if a client loses access, and the administrative oversight some firms actively want. A zero-knowledge model like Holdfast's removes the operator as a point of trust entirely, at the cost of those conveniences: there is no server-side search of encrypted contents, and no operator who can recover a lost passphrase.

03Delivery: the dead man's switch

This is the difference that defines the two products. Safe4 waits to be opened. Holdfast delivers itself.

Safe4 has no automated trigger. Access for a family member or executor is arranged in advance: the account holder, or the administering firm, invites the people who should have access, and when the time comes someone has to act on that access. It is a vault with a set of permissions, and it depends on a living person knowing the vault exists and stepping in to use it.

Holdfast is built around the trigger. The user checks in on a schedule. If a check-in is missed, a 7-day grace period runs with no escalation, then a 7-day escalation window sends up to 3 reminders through distinct delivery infrastructure, and if the user still does not respond, the encrypted vault and instructions are delivered to each nominated recipient automatically. On the Firm tier, the switch can alert the client's solicitor before recipient delivery, so the firm stays in the loop without having to run the process by hand.

The firm does not run the bereavement process. The switch does.

04Professional and firm features

Safe4 has over fifteen years of document-management depth. Holdfast Firm is newer and deliberately narrower, because it is a delivery product rather than a document-management system.

Safe4 offers deep, decade-old tooling aimed at firms that administer client documents day to day: per-account white-label, granular per-folder permissions and security groups, a full audit trail, WebDAV drive mapping so the vault appears as a network drive, an asset register, document signing with a verification record, bulk vault copy, and reporting. If your job is to manage documents on behalf of clients, this is a rich and proven toolset.

Holdfast Firm is built for a narrower job: getting the right encrypted material to the right people when a client dies. It offers white-label delivery, CSV bulk client invitation, per-client vault completeness scoring so a firm can see who still needs to finish setting up, missed-check-in solicitor alerts, referral tracking, and a written DPA. Holdfast is a delivery product, not a document-management system, and the Firm tier is scoped to that.

05Certifications and track record

We will be direct: on formal certifications and years in service, Safe4 leads today.

Safe4 holds Cyber Essentials, has been penetration tested under the GCHQ-administered IT CHECK scheme, hosts on ISO 27001 certified infrastructure, and holds an A+ TLS rating, backed by over fifteen years of continuous operation since 2010. For a buyer who weights formal accreditation and a long operating history, that is a genuine and current advantage.

Holdfast is operated by Nexus-SecTech Ltd, a UK company with a named director, registered with the Information Commissioner's Office. Its strengths are architectural and structural rather than certification-led. The encryption module is open source and hash-verified in the browser. The design is zero-knowledge, so the operator is not a point of trust. The public security page carries a warrant canary and an incident-disclosure commitment, and there is a documented business-closure and data-export procedure.

Holdfast's external penetration test and Cyber Essentials certification are on the near-term roadmap and are not yet held. We state that plainly rather than imply an accreditation we do not have. If certification already in hand is decisive for you today, that currently points to Safe4.

06Pricing

Different models for different jobs, so the headline numbers are not comparing like with like.

Safe4 is sold to individuals through will writers rather than bought directly. The typical arrangement is 3 months free, then £3.00 per month for the client, with a nominal 1GB of storage.

Holdfast publishes its rates openly:

• Free: £0. A starter vault to try the product.
• Personal: £5 per month or £45 per year.
• Family: £9 per month or £79 per year.
• Firm: £39 per month or £399 per year, with white-label delivery and a dedicated firm dashboard.

On the headline individual monthly price, Safe4 at £3.00 is lower than Holdfast Personal at £5. But the two are not the same purchase: one is a custodial document vault administered through a will writer, the other is a zero-knowledge vault with an automated delivery switch that you control directly. Compare what each one does before comparing the monthly figure.

07Choose Holdfast if

• Your clients want privacy from the provider itself, not just from outsiders.
• You want automated delivery that fires without staff intervention.
• You value zero-knowledge encryption and a crypto module you can inspect and verify.
• You are comfortable that formal certifications are on the roadmap rather than in hand today.
• Your firm is UK-based or international: Holdfast processes to UK and EU standards and welcomes firms worldwide.

08Choose Safe4 if

• You need a proven, certified document-management vault today, with Cyber Essentials and penetration testing already in place.
• You want deep document features such as signing, WebDAV drive mapping, and an asset register.
• You are comfortable with a custodial model and access that is arranged in advance.
• An established track record matters more to you than zero-knowledge privacy.

Based on public sources only, as of May 2026. Where a Safe4 detail could not be verified it was omitted rather than guessed. If anything here is out of date, please tell us at [email protected] and we will correct it.