Startup Security Checklist — 10 Security Steps Before You Launch
Startup Security Checklist — 10 Security Steps Before You Launch
TLDR: Most startups think about security after something goes wrong. By then, the cost — in money, reputation, and customer trust — is orders of magnitude higher than fixing it beforehand. This checklist covers 10 foundational security steps every startup should clear before launch. You don't need a full security team. You need the right habits in place from day one.
The Cost of Launching Insecure
Here's a stat that doesn't get quoted enough: according to the IBM's 2025 Cost of a Data Breach Report, companies with fewer than 500 employees paid an average of $3.31 million per breach — and unlike large enterprises, most startups don't survive a breach of that scale.
The harder truth is that the vulnerabilities responsible for most startup breaches are not sophisticated. They're basic. Exposed credentials in a public GitHub repo. No rate limiting on a login endpoint. A misconfigured S3 bucket. Things that take an afternoon to fix before launch and months to recover from after.
Going through this checklist before you go live is not about being paranoid. It's about not handing attackers easy wins.
The 10-Item Pre-Launch Security Checklist
1. HTTPS Everywhere
Every page, every API endpoint, every asset — served over HTTPS, no exceptions. HTTP traffic is unencrypted and can be intercepted trivially on any shared or public network. In 2026, there is no legitimate reason for any part of a web application to serve content over plain HTTP.
Use Let's Encrypt for free TLS certificates, enable HTTPS redirects so HTTP requests are automatically upgraded, and verify your configuration with SSL Labs' free server test.
2. Input Validation and Parameterised Queries
Never trust user input. Every field that accepts data from a user — forms, URL parameters, API request bodies — should be validated on the server side, not just the client side. And any interaction with a database must use parameterised queries or prepared statements, not string concatenation.
SQL injection consistently appears in OWASP's Top 10 vulnerability list because it remains widespread and because the fix is well-established. If your codebase is still building raw queries from user input, this is your highest-priority fix before launch.
3. MFA, Session Management, and Account Lockout
Implement multi-factor authentication for all admin accounts and, where feasible, for user accounts too. Sessions should expire after inactivity, tokens should be invalidated on logout, and login endpoints should implement account lockout or rate limiting after repeated failed attempts.
Without rate limiting, a login page is an open invitation to credential stuffing attacks — automated tools that try millions of username/password combinations harvested from previous breaches. This takes an hour to implement and prevents an entire category of attack.
4. Dependency Audit
Modern applications sit on top of dozens or hundreds of open source packages. Each one is a potential vulnerability. Before launch, run npm audit (Node.js), pip audit (Python), or the equivalent for your stack, and resolve critical and high-severity findings.
Automate this going forward. GitHub's Dependabot and tools like Snyk can alert you the moment a new vulnerability is published for a package your application depends on — before attackers start exploiting it.
5. No Secrets in GitHub
API keys, database credentials, private tokens, and cloud access keys must never be committed to your repository — even a private one. Secrets in version control get exposed through repository leaks, accidental public switches, and former team member access.
Use .env files for local development and a proper secrets manager — AWS Secrets Manager, HashiCorp Vault, or equivalent — for production. Before launch, scan your entire commit history with a tool like TruffleHog to catch anything that slipped through. If a secret has been committed, rotate it immediately — deleting the commit is not enough.
6. Error Handling — No Stack Traces to Users
When your application throws an error, the response a user sees should be a clean, generic message. It should never include a stack trace, a file path, a database error string, or internal variable names. That information is a detailed map of your application's internals, handed directly to anyone probing for weaknesses.
Configure your production environment to log verbose errors internally — you need that information for debugging — while returning sanitised messages externally. This is a configuration change, not a rewrite.
7. Access Control — Least Privilege
Every user, service account, and API key should have access to exactly what it needs and nothing more. An API key that only needs to read from one S3 bucket should not have write access to your entire cloud storage. A user role that manages blog content should not be able to access billing data.
Review every permission in your application before launch. This principle — least privilege — is one of the most effective and most consistently ignored security controls in early-stage products.
8. Security Headers
HTTP security headers are instructions your server sends to the browser that restrict what the browser is allowed to do with your content. They prevent a category of attacks — cross-site scripting, clickjacking, MIME sniffing — at almost zero implementation cost.
The key headers to implement before launch are Content Security Policy (CSP), HTTP Strict Transport Security (HSTS), X-Frame-Options, X-Content-Type-Options, and Referrer-Policy. Run your site through securityheaders.com — it gives you a free grade and exact remediation steps for anything that's missing.
9. Logging and Alerting Basics
You cannot respond to an incident you can't see. Before launch, establish baseline logging for authentication events (logins, failures, password resets), access to sensitive data, and application errors. Store logs somewhere separate from your application server so they can't be wiped by an attacker who gains access.
Set up at minimum one alert: repeated failed login attempts on a single account, or from a single IP address, within a short time window. This is the earliest signal of a credential stuffing or brute force attack in progress.
10. Third-Party Vendor Security Review
Your security posture is only as strong as the weakest vendor with access to your data or systems. Before launch, list every third-party tool, SaaS platform, or integration that touches your customer data. For each one: What data do they hold? How is it protected? What happens if they're breached?
Check whether each vendor is SOC 2 certified, review their data processing agreements, and remove access for any tool you're no longer actively using. Third-party breaches have become one of the most common root causes of startup security incidents — often affecting companies that had their own house in order.
After Launch: Security Doesn't Stop Here
This checklist gets you to a defensible baseline. It is not a one-time exercise.
Post-launch, the non-negotiables are regular dependency audits, periodic access control reviews as your team grows, and at least one external penetration test before you reach significant user scale or handle sensitive customer data. The cost of a pen test is a fraction of the cost of a breach — and what it surfaces is almost always something your internal team didn't know to look for.
How Kuboid Secure Layer Can Help
If you're approaching launch and want an expert set of eyes across your application before it goes live, we offer pre-launch security reviews designed specifically for startups and growing products. We look at exactly the areas on this checklist — and the things that aren't on it — to give you a clear, prioritised picture of what needs to be addressed before customers arrive.
You can find out more about what we do on our services page, or get in touch directly if you'd like to talk through your specific situation. We work with early-stage teams regularly and understand the constraints that come with that.
Final Thought
Launching is already hard enough. Security doesn't need to be an afterthought that makes it harder — it just needs to be part of the process. The items on this list are not complex. Most can be addressed in a single focused sprint. And clearing them before launch means your first conversation with customers is about your product, not a breach disclosure.
Build it right the first time. The shortcut isn't worth it.
Kuboid Secure Layer helps startups and growing businesses build secure foundations from day one. Explore our services or visit our blog for more guides like this.