The Startup Security Checklist Before You Raise Your Series A

Nobody raises a Series A with a security breach in the rearview mirror. But the uncomfortable truth is that most early-stage startups have security gaps that would surface in any serious due diligence process. The question is whether you find them first or whether someone else does.

We work with a lot of pre-Series A startups. Some come to us because an investor asked about their security posture during diligence. Others come because a prospective enterprise customer sent over a security questionnaire and they couldn't answer half the questions. A few come after something went wrong.

This is the checklist we wish every founder had before they got to any of those situations. It's not exhaustive, but it covers the things that actually matter at the seed-to-Series A stage.

Why this matters now (not later)

There's a common assumption in startup land that security is a "scale problem." You deal with it when you have real revenue, real users, real data. The logic makes sense on the surface: you have limited runway, a small team, and a hundred things competing for attention.

The problem is that the security landscape has shifted. According to IBM's 2024 Cost of a Data Breach Report, the average cost of a breach for organizations with fewer than 500 employees is $3.31 million.^[1] That number can be existential for a startup burning $150K a month.

Investors know this. Bessemer Venture Partners' 2025 State of the Cloud report found that 78% of enterprise software buyers now require SOC 2 compliance or equivalent security documentation before signing a contract.^[2] That means your security posture directly affects your ability to close deals, which directly affects your Series A metrics.

And if you're building with AI tools (Lovable, Cursor, Claude), the risk profile is different from what it was even two years ago. These tools produce functional code fast, but our recent research found critical vulnerabilities in the majority of AI-built apps we reviewed.

The checklist

We've organized this into six areas. Not all of them will apply to every startup, but if you're handling user data and charging customers, most of them do.

1. Authentication and access control

This is where the most critical vulnerabilities live in early-stage products. The auth system is what separates "anyone on the internet" from "your paying customers," and it's where AI-generated code fails most consistently.

If you're using Supabase, check your Row Level Security policies on every table. If you're using Firebase, verify your Firestore security rules aren't defaulting to open. These are the two most common database misconfigurations we find in startup environments.

2. Data protection

What data are you collecting, where does it live, and who can access it? Investors and enterprise buyers will ask these questions. You need clear answers.

If you're processing health data, you need HIPAA considerations from day one. If you're handling payment data directly (not through Stripe's hosted checkout), PCI DSS applies. These aren't "nice to have" frameworks; they're legal obligations with real consequences.

3. Secrets management

This is the one that trips up vibe-coded apps more than anything else. AI tools routinely hardcode API keys, database credentials, and service tokens directly into source code. Our reviews regularly surface Stripe secret keys, AWS credentials, and Supabase service role keys sitting in frontend JavaScript or committed to version control.

If you find secrets in your git history, rotating those credentials is the priority. Rewriting git history is nice but secondary; the credential is already exposed if the repo has ever been public or if any contributor's machine has been compromised.

4. Infrastructure and deployment

Your cloud environment configuration matters more than most founders realize. Misconfigured S3 buckets, overprivileged IAM roles, and exposed admin panels are consistently among the top findings in our startup engagements.

A common mistake at this stage is giving every developer admin access to the production cloud account. Set up proper roles early. It's much harder to tighten permissions retroactively than to start with them in place.

5. Organizational security basics

Investors don't just look at your code. They look at how your team operates. A five-person startup doesn't need a CISO, but it does need basic hygiene.

The offboarding point is bigger than people think. We've seen startups where former contractors still had push access to production repos months after their engagement ended. An access review takes an afternoon. A breach caused by a stale credential takes much longer to clean up.

6. Compliance readiness

You probably don't need full SOC 2 certification before your Series A. But you should be on the path, because the moment you start selling to mid-market and enterprise, it becomes a gating requirement.

Tools like Vanta, Drata, and Secureframe can accelerate SOC 2 readiness significantly. They automate evidence collection and continuous monitoring, which reduces the manual overhead from months of work to weeks. The investment typically pays for itself with the first enterprise deal it helps you close.

What investors actually ask about

Based on our work with startups going through diligence, here are the security questions that come up most often:

1. Have you had a penetration test? This is the most common question. A recent third-party pentest report is the single most credible security artifact you can produce.
2. What's your SOC 2 timeline? They don't expect you to have it yet. They want to see that you have a plan.
3. How do you handle customer data? Where it's stored, who can access it, how it's encrypted, and how long you keep it.
4. What happened with your last security incident? If you've had one, they want to know how you handled it. If you haven't, they want to know how you'd handle one.
5. Who's responsible for security on your team? It doesn't have to be a dedicated hire. It has to be someone's explicit responsibility.

Having clear, honest answers to these five questions puts you ahead of most seed-stage companies in a diligence process.

Where to start if you're behind

If you're reading this list and feeling behind, that's normal. Most startups at this stage have gaps. The goal isn't perfection; it's demonstrating that you take security seriously and have a credible plan to address the most critical risks.

Here's the priority order we recommend:

1. Run a secrets scan on your codebase today. This is the fastest win with the highest impact. Tools like TruffleHog are free and take minutes to run.
2. Audit your auth by testing whether API endpoints validate sessions server-side. Try accessing endpoints without a valid token. If they respond with data, you have a problem.
3. Check your database access controls (Supabase RLS, Firebase rules, or equivalent). These are the most common source of critical vulnerabilities in modern startup stacks.
4. Enable MFA on your cloud accounts, GitHub org, and email. This takes 30 minutes and eliminates an entire class of attacks.
5. Get a penetration test before your raise. A targeted security review gives you a clear picture of your risk, a remediation roadmap, and a report you can share with investors and customers.

Lorikeet Security Team

Penetration Testing & Cybersecurity Consulting

We've completed 170+ security engagements across web apps, APIs, cloud infrastructure, and AI-generated codebases. Everything we publish here comes from patterns we see in real client work.