How much does a code audit cost?

It depends on the size of the codebase, how many languages and platforms it spans, how deep you need the review to go, and whether the audit is a fixed-scope report or an open-ended engagement. A focused audit of one web application with a clear question ("is this safe to build on?") is a small, fixed piece of work. A full security, performance and architecture review across a web app, two mobile apps and an old backend is a much larger one. Ask for a scoped quote, not a day rate.

Is a fixed-price code audit better than an hourly one?

For most businesses, yes. A fixed price forces the auditor to define what will be examined and what you will receive, which is exactly what you need to compare quotes and to judge the result. Hourly suits open-ended investigations where nobody knows how deep the problems go, but it should still come with a cap and a weekly summary. Whichever you choose, insist on a written scope and a sample report before you commit.

What does a code audit include?

A good one covers architecture and structure, code quality and maintainability, security (dependencies, authentication, data handling, common vulnerability classes), test coverage and the state of the build and deployment pipeline, performance hotspots, and documentation. The output is a written report with findings ranked by risk, an estimate of the effort to fix each group, and a recommendation: stabilise, refactor in place, or rebuild parts. A list of lint warnings is not an audit.

How much should I budget for fixes after a code audit?

Treat the audit and the remediation as separate decisions with separate budgets. The audit tells you the size of the problem; you then decide how much of it to fix and in what order. A sensible report groups findings into what must be fixed before you build further, what should be fixed in the next few sprints, and what can wait. Ask the auditor to estimate each group so you can fund the first before committing to the rest.

Code Audit Cost: What Affects the Price

Code audit cost is set by four things: how much code there is, how many languages and platforms it spans, how deep the review needs to go, and whether you are buying a fixed-scope report or an open-ended investigation. A focused audit of a single web application with a clear question is a small piece of work with a fixed price. A full security, architecture and performance review across a web app, two mobile apps and a legacy backend is a project. Quotes that vary several-fold are usually describing different depths, and the cheapest one is often not an audit at all.

This post explains what drives code audit cost, how fixed-price and hourly audits differ, what a cheap audit leaves out, how to budget for the fixes that follow, and how to scope an audit so you pay for the answer you need and nothing else. If you want the definition first, we covered what a code audit is and what it covers separately.

What drives code audit cost

Size of the codebase

More code takes longer to read, and reading is most of what you pay for in code audit cost. Size is measured less in lines than in surface area: the number of screens, API endpoints, database tables, background jobs and integrations. A small app with a tangled core can take longer to audit than a larger one with a clean structure, because the auditor has to trace how things connect before judging them.

Languages and platforms

Each language and platform needs an auditor who knows it well. A system with a React front end, a Node API and a PostgreSQL database is one skill set. Add an iOS app in Swift, an Android app in Kotlin and a PHP admin panel from a previous vendor, and you need three or four people or one generalist taking longer. Older or unusual stacks (a PHP 5 application, a classic ASP.NET site, a custom framework nobody else uses) cost more because fewer people can read them quickly.

Depth

Depth is the lever with the widest effect on code audit cost, and the one vendors describe least clearly. Roughly, there are three levels:

Depth	What is examined	Typical output	Relative code audit cost
Health check	Structure, dependencies, obvious risks, test and deployment setup	Short report, traffic-light summary, recommendation	Low
Full audit	Everything above plus a read of the core modules, security review against common vulnerability classes, performance hotspots, data handling	Ranked findings with effort estimates and a remediation plan	Medium
Deep or regulatory audit	Line-by-line review of critical paths, threat modelling, compliance mapping, penetration-style testing	Evidence-grade report suitable for an acquirer, insurer or regulator	High

Most business buyers need the middle row. The first row is enough when the question is "should we keep this vendor's work or start again?" The third is for due diligence on an acquisition, a regulated product, or a system that has already been breached.

Access and documentation

An audit of a codebase with a working local setup, a readable README and a deployment pipeline moves quickly. One where the auditor has to reconstruct how to run the system, chase credentials from a departed developer, or reverse-engineer an undocumented database adds days before any judgement can be made. This is why vendors ask for access before they commit to a code audit cost.

Who is asking and why

An audit to decide whether to build on a vibe-coded prototype, an audit before buying a company, and an audit because the site went down twice last month are three different jobs with the same name. The purpose decides what to look at first and how much evidence the report needs to carry.

Code audit cost: fixed price versus hourly

Code audit fixed price offers suit most businesses better, and not only for budget certainty. A fixed price forces the vendor to write down what will be examined, to what depth, and what you will receive. That document is what lets you compare two quotes and what you hold the vendor to afterwards.

Hourly audits suit genuinely open-ended investigations: a system nobody understands, an incident with no obvious cause, or a very large codebase where the right first step is a few days of orientation before scoping the rest. Even then, insist on a cap, a weekly written summary, and a defined point at which the vendor converts the remaining work into a fixed scope.

A common and sensible structure is two steps: a short fixed-price health check that produces a map of the system and a ranked list of concerns, followed by a fixed-price full audit of the areas the health check flagged. You pay for the second step only where the first justified it, which keeps code audit cost tied to real risk rather than to the size of the repository.

Whichever model you choose, ask for:

The written scope: which repositories, which platforms, which concerns.
A sample report from a previous engagement, anonymised.
Who will do the work, and their seniority.
What is explicitly out of scope (penetration testing, load testing, infrastructure review are often separate).
How findings will be ranked and whether each group will carry an effort estimate.

What a cheap audit leaves out

A very low code audit cost usually means one of three things.

It is an automated scan with a cover page. Static analysis and dependency scanners are useful and every proper audit uses them, but their output is a list of warnings, many of them false positives and most of them unranked. An audit is a human reading the code and telling you what the warnings mean for your business.

It is a sales step for a rewrite. Some vendors offer free or near-free audits that reliably conclude the system should be rebuilt, by them. A credible audit considers stabilising and refactoring in place before recommending a rewrite, and says why. We laid out those options in legacy software modernisation: rehost, refactor or rewrite.

It covers only the code. The things that most often cause outages and security incidents are around the code: how secrets are stored, how deployments happen, whether backups are tested, how dependencies are kept current, who has access to production. A code review cost for a business app that excludes the build, deployment and infrastructure is pricing a fraction of the risk.

A cheap audit that misses an authentication flaw or an untested backup is more expensive than no audit, because it leaves you confident when you should not be.

Budgeting for remediation after the audit

The audit is the diagnosis; the fixes are the treatment, and their cost is a separate budget decision from the code audit cost itself. A useful report groups findings so that you can fund them in stages:

Fix before building anything else. Security holes, data at risk, a deployment process that can take the business down. These are usually a small number of items and the first thing any remediation budget covers.
Fix in the next few sprints. Structural problems that make every change slow or risky: missing tests on core rules, tangled modules, outdated frameworks with known vulnerabilities.
Fix when convenient. Style, minor duplication, documentation gaps.

Ask the auditor to estimate each group separately. Then you can decide to fund group one immediately, schedule group two across your normal development budget, and leave group three to accumulate until it matters. If the vendor who audits will also fix, make sure the audit scope and price stand on their own, so that the recommendation is not shaped by the work that follows. Our application modernisation and code audit service is priced that way: the audit is a fixed deliverable, and remediation is a separate written estimate you can take elsewhere.

One particular case deserves its own line. Codebases produced quickly with AI tools tend to look complete and fail in production in predictable ways; we described those in why AI-generated code breaks in production. An audit of such a system is often the cheapest step a founder can take before spending more, because it answers the question "is this a foundation or a prototype?" before the next invoice.

How to scope an audit to reduce code audit cost

Code audit cost falls fastest when you narrow the question. Some practical ways to do that:

State the decision the audit must inform. "Can we build the next six months of roadmap on this?" is a different scope from "Is this safe to put customer payment data through?" Name the decision and let the auditor scope to it.
Point at the parts that worry you. The checkout, the integration that keeps failing, the module nobody will touch. A targeted audit of the risky third of a system costs a fraction of a full one and finds most of the problems.
Provide access and documentation up front. A working environment, credentials, architecture notes, the previous developer's handover if any. Every day the auditor spends reconstructing your setup is a day you pay for.
Separate what you already know. If you know the test coverage is poor and the framework is out of date, say so; the audit can confirm it in an hour rather than discovering it over a week.
Choose the depth deliberately. A health check first, then a full audit of the flagged areas, costs less in total than a full audit of everything and leaves you with a decision at each step.
Avoid paying for a rewrite pitch. If a vendor's audit is free, treat the recommendation as a sales document and get a second opinion before acting on it.

Deciding how much audit you need

Code audit cost comes down to size, stack, depth and purpose. For most business applications the right purchase is a fixed-price full audit scoped to a named decision, preceded by a short health check if the system is large or undocumented, with remediation estimated in stages so you can fund the urgent part first. Avoid the lowest code audit cost unless the quote describes what it will read and what you will receive; avoid the free one entirely.

If you want a fixed-price scope for your codebase, book a free 30-minute discovery call. A senior engineer talks it through with you, and a written approach, timeline and estimate follow within two business days.

Code audit cost: what affects the price and how to pay less