Single-page apps move much of the application into the browser — routing, state, and too often, access-control decisions — while the real authority sits in the API behind them. Our SPA penetration testing tests both halves: the client-side risks unique to React, Angular and Vue, and the API authorization that ultimately protects your data.
The classic SPA mistake is trusting the client: hiding an admin route in JavaScript, enforcing a role only in the UI, or storing a token where any script can read it. We pull apart the front-end bundle, map every API call it makes, and then attack that API directly — because an attacker never uses your UI.
Because SPAs shift logic to the browser, teams routinely assume the front-end enforces security when it cannot. The result is authorization that evaporates the moment someone calls the API directly, plus secrets and endpoints sitting in a JavaScript bundle anyone can read.
What we test
Client-side access control and hidden functionality
Token storage and JWT handling
DOM-based XSS and client-side injection
API authorization behind the SPA
CORS and cross-origin misconfiguration
postMessage, WebSocket and third-party script risk
Common vulnerabilities we uncover
Broken authorization enforced only client-side
Insecure JWT/token storage and handling
DOM-based and stored XSS
IDOR and mass assignment on the backing API
Permissive CORS enabling data theft
Sensitive data and secrets exposed in JS bundles
Our methodology
Scoping & rules of engagement. We agree objectives, targets and boundaries for your single-page application (spa) penetration testing, so testing is safe, authorized and focused on what matters to your business.
Reconnaissance & mapping. We enumerate the full attack surface in scope, building a complete picture before any exploitation begins.
Manual exploitation. Our senior testers chain vulnerabilities by hand — going far beyond automated scanners — to prove real, demonstrable impact.
Analysis & reporting. Every finding is triaged, risk-rated with CVSS and written up with a copy-paste reproduction and clear remediation.
Remediation support & free retest. We support your team through the fixes and retest the remediated issues to confirm they are genuinely closed.
Tools & techniques
We start by treating your JavaScript bundle as documentation: extracting routes, roles, API endpoints and any leaked secrets, then rebuilding the full API surface the SPA talks to. Client-side, we test for DOM XSS, insecure token storage, and access control that exists only in the UI.
Server-side, we attack that API on its own terms — authorization, IDOR, mass assignment and CORS — proving whether the security you think the front-end provides actually holds where it counts.
When you need this engagement
You run a React, Angular or Vue single-page application
Your app is API-driven with client-side routing
You store tokens or sensitive data in the browser
You expose an API consumed by your front-end
You are launching or scaling a modern web app
What you receive
Executive and technical report with evidence
Client-side and API-side findings prioritised
Reproduction steps and remediation guidance
Bundle/secret-exposure review
Attestation letter where required
Complimentary retest after fixes
What’s included in your report
Every single-page application (spa) penetration testing engagement concludes with a comprehensive, board-ready report and a working session to walk your team through it. Your report includes:
An executive summary with overall risk posture for non-technical stakeholders
Detailed technical findings, each with a step-by-step, copy-paste reproduction
CVSS v3.1 severity ratings and business-impact context for every issue
Prioritized, actionable remediation guidance your engineers can apply directly
A complimentary retest to confirm fixes and update finding status
A formal attestation letter for customers, auditors and compliance programs
Standards & frameworks
OWASP Top 10OWASP ASVSOWASP WSTGJWT/OAuth best practice
Outcomes you can expect
After your single-page application (spa) penetration testing, you will have clear, evidence-based visibility into your real security risk — not a scanner’s guesswork. You will know exactly which weaknesses an attacker could exploit, what the business impact would be, and the precise steps to fix them in priority order. Teams use our findings to close critical gaps, satisfy customer and regulator security requirements, and demonstrate due diligence to their board. With a complimentary retest included, you also get documented proof that the issues are genuinely resolved.
Engagement details & logistics
Every single-page application (spa) penetration testing starts with a short, no-obligation scoping call to understand your goals, environment and constraints, followed by a fixed-price proposal and a clear statement of work. Most engagements are delivered fully remotely, with on-site work arranged where it genuinely adds value. Throughout testing we maintain an agreed communication cadence and escalate any critical, high-impact finding to you immediately rather than waiting for the final report. All work is performed under a signed NDA with strict data-handling controls, using safe, non-disruptive techniques and carefully coordinated rules of engagement to protect your production systems. On completion you receive your report and a walkthrough session, followed by a complimentary retest once your fixes are in place. Typical engagements are booked one to three weeks in advance, and urgent or pre-deadline testing can often be accommodated — just ask at hi@agentoffense.com.
Why organizations choose AgentOffense
Our single-page application (spa) penetration testing is delivered by senior offensive-security engineers who test the way real attackers do — manually, creatively and with a relentless focus on proving genuine, demonstrable impact. Here is what sets our engagements apart:
Manual, exploit-driven testing that chains vulnerabilities the way a real attacker would, going far beyond what automated scanners can find.
Reproducible proof for every finding, with copy-paste reproduction steps your engineers can follow and independently verify.
Honest severity calibration so you invest in fixing what genuinely matters and avoid wasting effort on false positives and noise.
Clear, business-focused reporting that speaks to engineers and executives alike, tying every issue to real-world impact.
A complimentary retest included, so you get documented proof that your fixes actually close the attack path.
Responsible, collaborative delivery with a named point of contact and secure handling of all data throughout the engagement.
Explore related services
Single-Page Application (SPA) Penetration Testing is frequently scoped alongside our other offensive-security services for broader coverage. Explore related engagements that complement it:
Web Application Penetration Testing — Manual web application penetration testing against the OWASP Top 10 and business-logic flaws. Exploit-driven testing with…
API Penetration Testing — REST and GraphQL API penetration testing against the OWASP API Top 10 — BOLA, BFLA, mass…
OWASP Top 10 Penetration Testing — OWASP Top 10 penetration testing — manual, exploit-led assessment against every OWASP risk category.
How much does Single-Page Application (SPA) Penetration Testing cost?
Every single-page application (spa) penetration testing is scoped and priced individually, so you pay for exactly the coverage you need — with no hidden extras. After a short, no-obligation scoping call we send a fixed-price quote, usually within one business day, with clear deliverables, a firm timeline and a complimentary retest included. The price of your single-page application (spa) penetration testing depends on the size and complexity of the target and the depth of testing required, so you always know the cost up front before any work begins.
