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Manual penetration testing for startups & SaaS

We find the flaws your scanners miss.

Manual penetration testing for web, mobile, API, cloud, and AI systems. Every finding comes with proof, a fix, and a free retest.

Book a scoping callSee how it works
  • 100+vulnerabilities disclosed
  • Manualattacker-led testing
  • Freeretest on every fix
Web
API
Cloud
AI
Mobile
ZeroSight360 emblem: an ouroboros around an eye

Five attack surfaces, tested from every angle.

What we test

Every engagement is scoped to your real attack surface and tested by hand against the standard your auditors and customers expect.

Web applications

Broken access control, auth and sessions, injection, business-logic abuse

OWASP WSTG, ASVS

APIs

BOLA and IDOR, broken authentication, mass assignment, GraphQL abuse

OWASP API Top 10

Mobile apps

Insecure storage, reverse engineering, runtime tampering, backend abuse

OWASP MASVS

Cloud

Over-privileged IAM, exposed storage, network controls, Kubernetes

CIS Benchmarks

AI agents and LLM apps

Prompt injection, tool abuse, RAG poisoning, excessive agency

OWASP LLM Top 10

Networks and full scope

External and internal networks, multi-surface engagements, social engineering

PTES, MITRE ATT&CK

How we break in

From first call to verified fix.

Watch a typical engagement play out: what we test, how we break in, what you receive, and how we prove the risk is closed. Most web and API tests take one to three weeks.

Why manual testing finds more. Scanners see patterns. We see your business.

Automated scanners are useful for hygiene. The flaws that lead to breaches usually need a person who understands how your product is meant to work.

  • Business-logic flaws

    Scanner
    Rarely
    ZeroSight360
    Tested by hand per role

  • Broken access control (IDOR / BOLA)

    Scanner
    Pattern-based only
    ZeroSight360
    Every object and role

  • Chained attacks

    Scanner
    No
    ZeroSight360
    Yes, to show real impact

  • False positives

    Scanner
    Many, unverified
    ZeroSight360
    Each finding validated

  • Proof of exploitability

    Scanner
    No
    ZeroSight360
    Request and response evidence

  • Fix guidance

    Scanner
    Generic
    ZeroSight360
    Code-level, per finding

  • Retest of fixes

    Scanner
    Re-scan only
    ZeroSight360
    Free retest, verified status

Reports your engineers can act on

No 200-page scanner dump. Each finding is written for the developer who has to fix it and the stakeholder who has to sign it off.

  • Severity and CVSS score for every finding
  • Proof: the exact request and response we used
  • Business impact in plain language
  • A fix your engineers can apply the same day
  • Free retest, with verified status in the final report

Finding 3 of 23

Critical

Invoice API returns any customer's billing records

Endpoint
GET /api/v2/invoices/{id}
CVSS 3.1
9.1
Impact
Any signed-in user can read every invoice by changing the ID.

GET /api/v2/invoices/48213 HTTP/1.1

Authorization: Bearer <token for account B>

HTTP/1.1 200 OK

{ "account": "A", "total": 18450.00, "card_last4": "4417" }

Fix
Check that the invoice belongs to the caller's account before returning it.

Status

Open
An illustrative finding, written the way our reports are.

100+

vulnerabilities responsibly disclosed

We report bugs to the companies you rely on.

The same people who test your product hunt vulnerabilities in public bug bounty programs, many rated critical or high.

See our disclosure record
GoogleCritical and high severity reports
MicrosoftSecurity vulnerabilities reported
NokiaApplication security disclosures
TecnoMobile security disclosures

When you need more than a report

Our engineering team builds products with the same attacker mindset. Use us to fix what a test finds, or to build something new that is secure from the first commit.

SaaS and web developmentFull-stack products threat-modeled from day one and pentested before launch.
Mobile app developmentReact Native and Flutter apps with secure storage and hardened API integration.
AI agents and automationAgents, chatbots, and workflows built with guardrails and least-privilege tool access.
“ZeroSight360 found critical auth bypasses two previous firms missed. Their manual testing depth is exceptional.”
Arjun M., CTO at a Series A fintech

Client names are withheld under NDA. References are available on request.

Questions buyers ask.

Anything else? Ask us on a free scoping call and get an answer from the engineer who would run your test.

How long does a test take?

Most web and API tests take one to three weeks from kickoff to report. We confirm the timeline during scoping.

What do you need from us?

Test accounts for each user role, the URLs or app builds in scope, API documentation if you have it, and agreed rules of engagement. Grey-box access is preferred because it gives the best coverage for the time spent.

Will testing affect production?

We use non-destructive techniques and test within agreed windows. Staging is preferred when it mirrors production; if we test production, the rules of engagement say exactly what is allowed.

What is in the report?

Every finding has a severity and CVSS score, request and response evidence, the business impact, and a code-level fix. The report opens with an executive summary for leadership.

Is retesting included?

Yes. After your team fixes the findings, we retest them for free and update the report with verified status you can share with customers and auditors.

Someone will find your vulnerabilities. Let it be us.

We’ll scope your test on a 15-minute call and send a fixed quote. Every enquiry gets a reply within 24 hours.

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