Fintech — Blockchain security for a fintech is the review of the systems that sit between ordinary users and a blockchain — wallets, on and off-ramps, payment rails, settlement logic and the APIs that drive them — where the money is real, the users are non-technical, and a single authorisation flaw affects every account at once.
Fintechs occupy the hardest position in this market. They hold user funds like a bank, ship at the pace of a startup, integrate a dozen third parties, and carry the reputational exposure of a consumer brand. The attack surface is correspondingly wide: an embedded wallet SDK, a custody provider, a liquidity partner, a KYC vendor, a webhook that triggers a payout, and a mobile app that signs transactions on a device you do not control.
In our experience the highest-severity findings at fintechs are rarely in a contract. They are in the API layer: an object-level authorisation gap that lets one account read or move another's balance, a withdrawal endpoint whose idempotency breaks under concurrency, a webhook accepted without signature verification, or a customer-support tool with more authority than any external attacker would need. These are ordinary application security failures made expensive by the fact that settlement is irreversible.
We test the whole path: the contract or custody integration, the backend that authorises it, the mobile and web clients that trigger it, and the operational tooling around it. The deliverable is written for a team that will ship a fix this week, and it is structured well enough to hand to a banking partner or payment processor doing their own due diligence on you.
We fix a commit hash, agree the in-scope contracts and read your architecture docs, then build a threat model: who the actors are, what the trust boundaries are, and which invariants must never break. Nothing is reviewed against assumptions we have not written down.
Line-by-line review by at least two auditors working independently, focused on authorisation, accounting, upgrade paths, external integrations and the gap between what the code does and what the documentation claims it does. Most critical findings come from this phase, not from tooling.
Static analysers appropriate to the language, plus property-based fuzzing and invariant testing to push the system into states no unit test covers. Tooling is used to widen coverage, never to replace the manual pass.
Candidate findings are proven on a forked network with a working proof of concept. We report what an attacker can actually do and what it costs them, not a theoretical severity label.
Every finding gets a severity rating, reproduction steps, the affected code, the impact in concrete terms and a specific remediation. You get a draft for discussion before anything is finalised.
We re-test every remediation against the original proof of concept and check that the fix has not opened a new path. The final report is yours to publish.
Yes, and it changes what to test. Your provider secures their vaults; your API keys, approval workflow, withdrawal logic, limits and integration remain yours, and that boundary is where fintech custody incidents concentrate.
Authorisation flaws in the API layer. In most fintech engagements the highest-severity finding is an endpoint that trusts a client-supplied identifier, not a smart contract bug.
Yes. Testing runs against a staging environment mirroring production, with read-only reconnaissance against production, and anything intrusive confined to an agreed window.
Usually yes. Tell us who is asking and what they require, and we will scope the engagement so the deliverable answers their questionnaire rather than requiring a second engagement.
Scoping call within a day, fixed quote within 24 hours of seeing the scope, and typical start within one to two weeks depending on the size of the estate.
A repository or contract address, a commit hash to freeze the scope, whatever architecture or spec documentation exists, and a point of contact who can answer design questions. If documentation is thin we will write our understanding of the system back to you and ask you to confirm it — that step alone catches design-level bugs.
A single token contract is 24–48 hours. A typical dApp or mid-sized protocol runs one to two weeks. Large DeFi systems, L2s, bridges and ZK circuits are scoped per project after we have seen the code. We will give you a fixed timeline with the quote, not an estimate that moves.
Send the repository and a commit hash through the contact form, message @bugtester25 on Telegram, or book a 30-minute scoping call. 200+ protocols audited · $4B+ secured · 0 hacks post-audit. Prefer email? info@safeedges.in.