Audit, bug bounty, or formal verification: what each one buys
Teams often ask whether they have been audited as if security were a single switch. It is not. An audit, a bug bounty, and formal verification are three different instruments, with different shapes of assurance, different costs, and different timing. Spend on the wrong one for your situation and you can pay a great deal while leaving the real risk untouched. The way to choose is to understand what each one genuinely gives you, and what it leaves open.
An audit
An audit is a time-boxed expert review of a fixed version of your code, usually before launch or before a major change. What it buys is a broad, intelligent human read of the system against your threat model: a skilled reviewer thinking about how your specific design fails, finding issues a checklist would not, and handing you a report with reproducible findings and remediation.
What it does not buy is a guarantee of completeness or any coverage of code written after the review ends. An audit is a snapshot. It reduces risk substantially, and it is honest about the limits of doing so, which is why a good report states what it did not examine. For most teams it is the right first instrument, and the foundation the others build on.
A bug bounty
A bug bounty is a standing offer: anyone who finds a valid vulnerability in your live system gets paid, scaled to severity. What it buys is continuous adversarial attention from a large and varied pool of researchers, over time, after launch, at a price that tracks the seriousness of what they find. It keeps eyes on the code long after any single review is over.
What it does not buy is pre-launch assurance. A bounty operates on a deployed system with real value at stake, which is precisely the wrong moment to discover a critical flaw, and it offers no guarantee that anyone will look at the part that matters before an attacker does. A bounty is an excellent complement to an audit and a poor replacement for one.
Formal verification
Formal verification proves, mathematically, that the code satisfies properties you have stated precisely. What it buys is certainty, of a kind the other two cannot offer, about the specific properties you specify: that a vault never pays out more than it took in, that supply is conserved, that an invariant holds across every possible input rather than the inputs a tester happened to try.
What it does not buy is anything about properties you did not specify, or any assurance that your specification captures what you actually meant. It is exhaustive within a narrow frame, and the frame is yours to draw correctly. It is also the most expensive and most specialized of the three, which is why it is best aimed at a small set of critical invariants on core components rather than at an entire codebase.
How they layer
These are not competing choices. They cover different gaps, and the strongest programs use them as layers in sequence:
- Before launch, an audit gives you a broad human read against your threat model and a report you can act on.
- For the invariants that must never break, formal verification turns a few critical properties from "tested" into "proven."
- Once value is live, a bug bounty keeps adversarial attention on the system as it changes and as new researchers arrive.
Each catches what the others structurally cannot. An audit will not watch your code for the next two years. A bounty will not protect you on day one. Formal verification will not tell you about the property you forgot to write down. Layered, they leave far less room than any one of them alone.
What we would tell you
Start with a real audit. Add formal verification for the handful of invariants whose failure would be fatal. Open a bug bounty once there is value to defend. And keep in mind that none of them is a guarantee.
A clean audit report reduces risk within stated limits. It does not certify safety, and the same honesty applies to all three instruments. If you want help deciding where your budget does the most good, that conversation is one we are glad to have before any engagement. For what to expect from the audit itself, see what a good audit report actually contains.
If you are weighing how to spend a security budget across these instruments, we will give you a straight answer about what your system needs. See our services or start a conversation.