E-commerce security audit before Black Friday. How to avoid losing data and revenue in 2026?
TL;DR - Quick summary
- Revenue protection: Malicious traffic (bots, DDoS) during peak sales can choke your stack and block real buyers. A security review finds those gaps before attackers do.
- Hard testing: We validate cloud architecture (AWS), API security in microservices (NestJS) and database hardening (PostgreSQL) to reduce personal-data leaks (GDPR).
- Technical foundation: Headless e-commerce systems we build and audit lean on MedusaJS v2, isolating payments from the presentation layer (Next.js).
- Budget certainty: Our DDT (Discovery, Design & Technology) process can be followed by a fixed-price guarantee to remediate the issues we discover.
The problem: checkout fails on the biggest sales day of the year
It is Friday, 6 p.m. Black Friday kicks in. Marketing spend pulls massive traffic. Then checkout stops responding. Engineering assumes organic load-until an hour later the truth appears: a script hammers an unprotected search endpoint 10,000 times per second and locks the database.
Real customers cannot pay. Competitors win while you lose hundreds of thousands in revenue and risk exposing user data.
In 2026, attacks on online stores are industrialized. GMI Software (16+ years, 120+ systems) knows hope is not a strategy. Skip a controlled security review months before peak and you accept paralysis risk.
No audit (reactive) vs a security review (preventive)
Leaders often treat audits as optional-until an incident. Compare the economics:
- No audit (reactive): You only pay for steady-state hosting. After a breach (for example accounts taken via a legacy Magento flaw) you lose peak-weekend revenue, fund legal counsel, GDPR fines and PR firefighting.
- Preventive security review (GMI): You fund a controlled code and infra audit a month before peak. Our engineers run penetration testing, ship rate limiting and AWS edge rules, and patch code paths. Ads keep converting while you sleep.
How we harden commerce before peak (GMI stack)
Commerce security is a system. GMI Software engineers in Gdansk focus on three vectors:
- Infrastructure (AWS and Docker): We test DDoS exposure, deploy WAF (Web Application Firewall) patterns and container scaling so a TikTok traffic spike does not flatten the fleet.
- API and microservice tightness (NestJS): In headless stacks the API is the blast radius. We review JWT handling and hunt SQL injection across endpoints.
- B2B/B2C data isolation (PostgreSQL RLS): For marketplaces we verify row-level security so a bug cannot leak one tenant invoices to another-critical on CRM-class work such as Berg System.
SFD, built by GMI with React Native, handles huge transaction volumes during peaks, with 100,000+ downloads, a 4.9★ App Store rating and a Mobile Trends Awards 2025 nomination.
What does the audit and remediation cost?
Security is math - you invest a fraction of potential losses to protect all revenue.
- Audit budget: A standard headless security review (for example MedusaJS v2 plus Next.js) with load testing typically lands PLN 15,000-35,000.
- Remediation budget: Critical architectural debt (legacy monolith cart logic) can require PLN 80,000-150,000 refactors.
Leaders fear open-ended T&M bills after findings. GMI Software changes that. We fold the audit into DDT (Discovery, Design & Technology), publish a firm estimate and offer a fixed-price guarantee for fixes inside the agreed scope. You receive 100% IP rights to the hardened code.
Frequently asked questions
- Why run an e-commerce security audit before Black Friday?
- Black Friday and the holidays drive your highest traffic, which attackers use to hide DDoS or card-data theft inside legitimate requests. Hardening a month ahead protects the year’s biggest revenue window.
- What are load and penetration tests inside a security review?
- Load tests simulate sudden traffic to see if servers and PostgreSQL hold. Penetration tests are controlled offensive exercises-for example targeting a MedusaJS admin surface-to find and fix issues before criminals do.
- Are headless e-commerce platforms safer than monoliths such as Magento?
- Generally yes. Headless, API-first stacks separate the Next.js storefront from payment logic and databases (MedusaJS / NestJS). A small frontend flaw does not automatically expose orders and credentials the way a tightly coupled monolith can.
- What are the most common API security gaps in online stores?
- Common issues include missing rate limiting that lets bots mass-create accounts, broken object-level authorization (BOLA) that leaks another shopper’s cart, and SQL injection on API endpoints.
- Does GMI Software guarantee fixes for security findings?
- Yes. Audits align with our DDT methodology. After we map findings we deliver a precise report and can offer a fixed-price guarantee for remediation and refactors inside the agreed scope.
Content updated: March 31, 2026