Secure Code Review & Application Security (AppSec / DevSecOps)
Fixing a security flaw while code is being written costs a fraction of fixing it after release, and far less than fixing it after a breach. Secure code review and application security put security checks inside your development process. Expert reviewers read the code that matters most, and automated tools check every commit.
Mutex Systems reviews code in languages including Java, C#, JavaScript and TypeScript, Python, Go and PHP, aligned to OWASP ASVS. We set up DevSecOps pipelines with SAST, software composition analysis, secrets and IaC scanning. We are a software company too, so our advice works for real delivery teams.
Or call our London office on 020 3307 529901Why it matters now
The risk behind this service
Based on incidents and figures in our UK & Europe threat report.
- Web applications were the starting point for many 2026 retail breaches. Flaws such as broken access control are easiest to find in code.
- Software supply-chain attacks through open-source packages and leaked secrets in repositories keep rising.
- Enterprise customers and regulators now ask for evidence of a secure development lifecycle: ISO 27001 controls 8.25 to 8.29, SOC 2 and PCI DSS requirement 6.
Who this is for
- SaaS and fintech product teams releasing frequently
- Organisations preparing for SOC 2, ISO 27001 or PCI DSS
- Banks and payment firms with in-house development
- Companies acquiring software or reviewing a supplier’s code
- Teams adopting AI coding assistants
- Start-ups preparing for enterprise due diligence
02Services
What we deliver
Manual Secure Code Review
Expert review of authentication, authorisation, input handling, cryptography and business logic in your most critical code.
Learn moreThreat Modelling
Design-stage workshops to identify threats and controls before code is written.
SAST Setup & Tuning
Static analysis in CI/CD, tuned to cut false positives so developers trust the results.
Software Composition Analysis (SCA)
Find vulnerable and risky open-source dependencies, and generate SBOMs.
Secrets & IaC Scanning
Detect leaked keys and tokens and insecure Terraform, Bicep or Kubernetes manifests in pull requests.
DevSecOps Pipeline Design
Security gates, branch protection and signed builds across GitHub, GitLab or Azure DevOps.
Learn moreAI & LLM Application Review
Review of prompt handling, tool permissions and output handling against the OWASP LLM Top 10.
Learn moreDeveloper Security Training
Hands-on OWASP Top 10 sessions using examples from your own codebase.
Learn more03Business impact
What application security changes
How building security into development compares with testing only before release.
| Factor | Test only before release | ● With Mutex AppSec |
|---|---|---|
| Cost of fixing | Flaws found late need rework, hotfixes and emergency releases. | Flaws caught in pull requests, when they are cheapest to fix. |
| Risk | Logic flaws and vulnerable libraries reach production. | Critical code reviewed by experts; dependencies checked on every build. |
| Delivery speed | Security reviews block releases at the last moment. | Automated checks run continuously; little last-minute work. |
| Customer trust | No answer to "how do you build securely?". | Documented secure SDLC and evidence for due diligence. |
| Developer skills | The same mistakes repeat. | Training on real findings raises team capability. |
04How it works
How an engagement runs
- 1
Scope
Agree repositories, languages, critical features and goals.
- 2
Threat model
Identify the highest-risk components and data flows.
- 3
Review
Automated scanning followed by manual review of critical code paths.
- 4
Report & fix
Findings with code-level fixes, discussed with developers.
- 5
Embed
Pipeline checks and training so issues do not return.
What you receive
- Code review report with code-level fixes
- Threat model for critical features
- Configured SAST, SCA, secrets and IaC checks
- Secure SDLC documentation for audits
- Developer training session
05Compliance
Frameworks and regulations this supports
OWASP ASVS
The verification standard used as the code review baseline.
OWASP Top 10
The most critical web application risks, covered in every review.
ISO 27001:2022
Controls 8.25 to 8.29: secure development, coding and testing.
PCI DSS v4.0
Requirement 6 covers secure development of payment software.
SOC 2
Change management and secure development support the Security criteria.
OWASP LLM Top 10
Risks specific to applications built on large language models.
grComply · GRC platform
Code findings linked to compliance, without sharing your code
grComply’s code-scanning workflow runs inside your own GitHub Actions, so your source code never leaves your environment. Only findings are sent to grComply, where they are tracked and mapped to ISO 27001, SOC 2 and PCI DSS secure-development controls.
Explore grComply- Scans run in your own GitHub workflows
- Findings mapped to secure-development controls
- Fix tracking with owners and due dates
- Evidence of a secure SDLC for auditors
What is a secure code review?
A secure code review examines application source code to find security flaws such as broken access control, injection and weak cryptography. It combines automated scanning with manual review by experienced security engineers.
Is code review better than penetration testing?
They complement each other. Code review finds flaws in logic and hidden code paths that testing may not reach. Penetration testing proves what can be exploited in the running system. Critical applications benefit from both.
Do you need full access to our source code?
For manual review, yes, for the agreed repositories, under NDA and secure access arrangements. For continuous scanning through grComply, the scans run in your own GitHub workflows and only findings leave your environment.
Which languages do you review?
Common languages including Java, C#, JavaScript and TypeScript, Python, Go and PHP, along with infrastructure-as-code and mobile code. Ask us about others.
What is DevSecOps?
DevSecOps means building security checks into the development and deployment pipeline, such as static analysis, dependency checks, secrets scanning and IaC checks, so security happens continuously instead of only before release.
Can you review AI-generated code?
Yes. AI-assisted code needs the same review. We also check AI features themselves for prompt injection and excessive permissions.
How much does a code review cost?
It depends on the size of the codebase, the languages and how deep the review goes. We send a fixed-scope proposal after a scoping call.
Build security into every release
Tell us about your codebase and pipeline. Reply within one working day, or call 020 3307 5299.