Every second your checkout lags, you are actively donating revenue to your competitors. And for most Magento stores, performance lag is far from the only symptom. For all that this platform is fantastic for e-commerce businesses, many store owners face issues like weeks spent trying to resolve a problem that snuck up on them after a minor ‘quick’ upgrade, or trying to understand why their shop has suddenly started lagging for no good reason.
If your store feels like it’s constantly fighting your growth plans instead of supporting them, you don’t need more band-aids. You need a comprehensive Magento code review that goes beyond an automated scan that spits out generic errors. A proper Magento code audit is a targeted, deep-dive diagnostic of your custom code, third-party extensions, and database configurations, designed specifically around the unique ways Magento tends to break, drag, and block upgrades.
The article below breaks down each of the five pillars for a thorough code review from the perspective of an actual auditor. Read it to know what you should expect from a reliable team auditing your Magento store and how to tell a highly actionable, revenue-saving audit apart from an automated report that just ticks boxes.
Core Code Changes and Improper Overrides: Why a Magento Code Audit Starts Here
Magento is built to be extended without touching its core. You add features through your own modules and adjust existing behavior via supported hooks rather than editing core files. Trouble starts when a previous developer took shortcuts, such as editing core files directly or overriding core classes in ways that work against the framework rather than with it.
The result is a store that feels fragile and throws up issues such as:
- A small change in one place that breaks something unrelated somewhere else
- Bugs that reappear after every deployment
- New features that take far longer than they should, because the code underneath them is unpredictable
An auditor’s first job is to compare your core against a clean copy of Magento and identify every place it has been changed. They check whether your customizations use supported extension points or override core logic in risky ways, and they flag the changes that will cost you the most later. We see this pattern well beyond Magento. For example, in a backend audit for Complete Network, our reviewers found that the team had overridden their framework’s built-in features with custom code that did the same job but less safely. To help the client, we documented every instance with a fix and a time estimate. Magento stores tell the same story, just with different file names.
Extension Conflicts: What a Magento Code Audit Checks in Your Third-Party Modules
Few Magento stores run on the core alone. A typical store carries dozens of extensions, each a piece of software written by someone else, with its own quality and assumptions. Install enough of them, and they start stepping on each other.
If your store began behaving strangely right after you added a plugin, this is usually why. Two extensions can try to modify the same part of Magento, and the one that loads second wins, often silently. However, an extension you installed years ago may have been abandoned by its maker and is now quietly incompatible with everything around it. Meanwhile, others hook straight into checkout, which is the worst possible place for a conflict to hide.
When we run this part of the Magento code audit, we inventory every extension you have, note which ones touch sensitive areas such as checkout and payments, and flag those that are outdated, abandoned, or in conflict. Just as useful, a good review often finds extensions you no longer need because Magento now does the same thing natively. Retiring them makes your store simpler, cheaper to maintain, and easier to upgrade.
Why Is My Magento Store Slow After Customization?
A Magento store usually slows down after customization because custom code queries the database for far more than it needs, repeats work it should do once, and disables the caching that keeps pages fast. Each of those is a specific, findable problem, and each one is common.
The most frequent culprit is code that loads a full set of records when a simple count or a single field would do, or that runs a fresh database query for every item in a loop instead of fetching everything at once. On a catalog with thousands of products, that difference turns a fast page into a crawling one. Close behind are customizations that mark parts of a page as uncacheable, which quietly disables Magento’s full-page cache for that whole page, and misconfigured caching or indexing that forces the store to rebuild data it should have kept ready.
Online stores are unusually sensitive to speed because every extra second compounds across category pages, product pages, and checkout, according to the 2025 Web Almanac by HTTP Archive. A performance-focused Magento code audit profiles your slowest pages, traces the delay back to the exact piece of custom code behind it, and tells you which fixes will move the needle most, so you spend effort where it actually pays off.
Checkout and PCI Security: The Highest-Stakes Part of a Magento Code Audit
Checkout is where your custom code meets your customers’ card data, which makes it the part of the store you least want a stranger poking around in. It is also exactly where attackers focus.
Since March 31, 2025, the Payment Card Industry Data Security Standard (PCI DSS) version 4.0.1 has required online stores to actively manage the scripts running on their payment pages, under Requirements 6.4.3 and 11.6.1. Every script has to be authorized, checked to ensure that it has not been altered, and watched for tampering. The rule exists because of e-skimming, where an attacker slips a few lines of code onto a checkout page and quietly copies card numbers as customers type them. A custom or heavily modified Magento checkout is a prime hiding spot for exactly that.
This is the most careful part of the Magento code audit we provide. Our experts review every customization in the checkout flow, catalog the scripts loading on your payment pages, confirm that admin access is properly locked down, and hunt for credentials accidentally left in the code. That last one is not rare. In an audit of Adoorabelle, we found payment system keys hardcoded directly into the source code, exposing them to anyone who could read it. If you want to know what to look for, check out our security code review checklist.
Upgrade Readiness: How a Magento Code Audit Prevents a Failed Adobe Commerce Migration
Every Magento store is on a clock, and most owners do not realize how little time they have. Adobe’s own lifecycle policy already ended support for version 2.4.5 in August 2025, and support for 2.4.6 ends in August 2026. Once a version reaches end of support, Adobe stops shipping security and compliance patches for it, and it never covered your customizations or third-party extensions in the first place. Running an unsupported, heavily customized store is a risk that grows quietly every month.
The catch is that customized stores are highly beneficial from a business perspective, but they are also precisely the ones whose upgrades fail. The core changes from the first section, the abandoned extensions from the second, deprecated code, and an outdated version of PHP, the language Magento is built in, are all upgrade-blockers. You usually discover them halfway through a migration, when the budget is already committed, and the timeline is already slipping.
An audit flips that order around. It finds every blocker before you spend a cent on the move, so you walk in with a full list of what has to be fixed, in what order, and roughly what it will take. An open-ended, nerve-racking project turns into a planned one with a known scope. If a version deadline is bearing down on you, this is the single most valuable thing an audit does.
Here is the difference in plain terms, pillar by pillar:
Core code changes
Flags a generic “core file modified” warning
Traces the override to its exact class, judges whether the pattern is risky, and estimates the fix
Extension conflicts
Lists which extensions are installed
Flags which ones fight each other, which are abandoned, and which Magento now replaces natively
Performance
Reports a page-speed score
Traces the slow page to the exact query or cache setting causing it
Checkout and PCI DSS 4.0.1
Confirms HTTPS is present
Inventories every payment-page script, checks admin access, and hunts for hardcoded credentials
Upgrade readiness
Checks the Magento version number
Finds every core, extension, and PHP-version blocker before a migration starts
Who Should Run Your Magento Code Audit, and What It Costs
One rule matters more than any other here: the team that built your store, or the one hoping to rebuild it, is the wrong team to evaluate and audit it. They have every reason to soften the findings or steer you toward the work they want to sell. An honest picture comes from an independent reviewer with no stake in the answer. That is why our reviewers always work from outside your original development team, and why the report you get is written in plain language, sorted by severity, with a time estimate attached to every issue so you can decide what to fix now and what can wait.
There are no fixed service packages because the scope decides everything. A store with light customization and a handful of extensions is a very different job from a decade-old build with a hundred modules and a custom checkout. What you are after shapes it too, whether you need a focused review of the code or a full software audit that also covers architecture, infrastructure, and testing. The factors that most affect the price are your store’s size and complexity, how deeply it has been customized, and how many extensions it carries. Redwerk has spent two decades reviewing and building software, including e-commerce platforms for clients across North America and Europe, and our software audit work is recognized by the International Association of Outsourcing Professionals (IAOP).
If your store is dragging, your last upgrade was painful, or you are not sure what a former team left behind, an audit gives you a clear, prioritized picture before you spend anything on fixes. Our code review team will scope your store, sort the findings by what actually matters to your business, and send you a free estimate. Give us a call and let’s work on a roadmap for your store’s quick improvement.
See how we audited Complete Network's quote management software Project Science, achieving an 80% increase in code maintainability
