What this is

Some systems carry more weight: they hold personal or health data, move money, sign things, or run infrastructure. For these we work differently from the first day: we write down who could attack, what they would want, and what stops them, and the build follows from that. Security is not a phase at the end.

What you get

A threat model in plain language, reviewed with you, kept up to date as the system changes.
Hardened defaults: strict content security policy, least-privilege service accounts, secrets in a managed vault, encryption at rest and in transit, short-lived tokens, dependency pinning and scanning.
An audit trail that answers "who did what, when, from where" for every sensitive action, stored where it cannot be edited.
Access through Zero Trust rather than VPNs and shared passwords. Admin interfaces that are simply not reachable from the open internet.
A code review by a second engineer on every change that touches auth, money or data access.
Documentation an auditor or a client's security team can read: data flows, retention, subprocessors, incident process.

Typical scope

A system that handles personal data under GDPR, with data subject requests, retention and deletion built in.
A payment or payout flow with reconciliation, idempotency and fraud checks.
A security review and hardening pass on a system you already run, with a prioritised list and the fixes done.

How we think about it

// Sensitive actions are explicit, authorised, and recorded in one place.
await guarded("payout.create", { actor, subject: payout.id }, async () => {
  authorize(actor, "payouts:create", payout.accountId);
  await payouts.create(payout, { idempotencyKey: payout.requestId });
});

Boring technology, applied strictly. No clever crypto, no home-made auth. Standard building blocks, configured correctly, verified.
Assume breach. Segmented access, short-lived credentials, logs that survive the compromise of the thing they log.
Say what we do not do. We are engineers, not a certification body. For formal attestations we work alongside your auditor and give them what they need.

Timeline

Three to twelve weeks. The threat model and architecture come first and take one to two weeks; they are a deliverable on their own if you want to stop there.

Good fit if

You can name the data and the regulations that apply, or want help naming them.
Your organisation will actually use the audit trail and the access controls once they exist.

Security practices for the baseline we apply to every project, not only these.
Backend systems and APIs
AI and LLM integration for model use under these constraints.

High-security systems