API Security for Startups: First Steps and What It Costs
A 30-day API security plan for startups, with a cost table of free tools and published prices. Start with what is free and add cover as you grow.
Startups handle sensitive data long before they can afford a security team: customer records, payment details, health data. None of it waits for your Series B. Effective API security does not need an enterprise budget. It needs the right order of work, and a clear view of what each step costs.
What should a startup do first about API security?
Start with what costs nothing: list every endpoint, require authentication on all of them, and check object ownership on every request. Then add a tool that watches live traffic, because prevention eventually fails. Free plans and open-source tools cover month one; add paid cover as traffic, customers and risk grow.
A 30-day API security plan
| Days | Focus | Do this | Done when |
|---|---|---|---|
| 1 to 7 | Know what you expose | Build an inventory of every endpoint from your routes, gateway configuration and live traffic. Require authentication on every one, “internal” endpoints included | Every endpoint has an owner and needs a credential |
| 8 to 14 | Authorisation | Add an object-ownership check to every request that takes an identifier. Default new endpoints to deny | A test user cannot read another user’s records by changing an ID |
| 15 to 21 | Input, limits and logs | Validate request bodies against a schema. Rate-limit login and other sensitive endpoints. Log authentication events and authorisation failures, never secrets | Malformed requests are rejected, and every failed login is logged |
| 22 to 30 | Watch and respond | Put a tool on live traffic, send its alerts to where your team already works, and write a one-page response plan | An alert reaches a person, and they know what to do next |
The days 8 to 14 work matters most. The OWASP API Security Top 10 ranks broken object level authorisation (BOLA) first: an API that returns someone else’s data because nobody checked who owns it. No firewall fixes it for you.
What API security costs
Prices as published in October 2026.
| What | Cost | Notes |
|---|---|---|
| Authentication, ownership checks and schema validation in your own code | Free, apart from engineering time | The biggest risk reduction per hour spent |
| Rate limiting in your API gateway, framework or reverse proxy | Usually included | Configure it per endpoint, not only globally |
| Open-source API scanners for pre-production testing | Free | Finds known flaws before release; does not watch live traffic |
| OWASP cheat sheets and guidance | Free | The reference for what to fix first |
| Runtime API security, Cyron Free | $0 | 5 requests a minute, no card, no time limit |
| Runtime API security, Cyron paid plans | $15 to $165 a month | Lite $15 (60 requests a minute), Essential $25 (120), Standard $65 (300), Premium $165 (600). Annual billing saves two months |
On Cyron pricing, behavioural intelligence comes with Essential and above. The AI analyst comes with Standard (3,000 analyses a month) and Premium (8,000). A 14-day trial of behavioural intelligence and the AI analyst lets you judge both before you pay. For higher volumes, talk to us.
Start with authentication
Before detecting attacks, make sure you know who is making each request.
Use standard protocols. OAuth 2.0 for delegated authorisation, JWTs for stateless authentication. Don’t invent your own token scheme; the security edge cases are brutal.
Require authentication everywhere. Every endpoint. No exceptions for “internal” or “low-risk” APIs. Attackers find those first.
Use short token lifetimes. Access tokens should expire in minutes to hours, not days. Use refresh tokens for longer sessions.
Build authorisation into your architecture
Authentication confirms identity. Authorisation decides access. Three of the ten OWASP API risks are authorisation failures.
Check object ownership on every request. When a user requests /orders/123, verify that order 123 belongs to them. Every single time.
Use middleware for common checks. Don’t repeat authorisation logic in every endpoint. Centralise it, so a change applies everywhere.
Default to deny. New endpoints should be inaccessible until explicitly permitted. Security by default beats security by remembering.
Validate everything
Never trust input from clients: not query parameters, not headers, not request bodies.
Define schemas for all inputs. Use JSON Schema, OpenAPI specifications or your framework’s validation. Reject requests that don’t conform.
Shape your outputs too. Don’t return raw database rows. Map responses to defined schemas that leave out internal fields.
Watch for type coercion. user_id=123 versus user_id=123 OR 1=1. Strong typing stops many injection attempts before they reach your database.
Rate limit aggressively
Rate limiting prevents abuse and buys time when attacks happen.
Apply limits per endpoint, not just globally. Login endpoints need strict limits. Public search can be more permissive.
Make limits part of the contract. Document them, and return the remaining quota in response headers.
Limit at several levels. Per address, per user and per API key. Each level catches a different pattern.
Log with intent
When something goes wrong, logs are your evidence, but only if they hold the right information.
Log authentication events. Successful logins, failures, token refreshes and logouts, with source addresses and user agents.
Log authorisation failures. When users try to reach resources they shouldn’t, record it. These are early attack indicators.
Never log credentials or sensitive data. Passwords, tokens and personal data in logs create new vulnerabilities. Redact them.
Don’t skip monitoring
Prevention fails. When it does, detection speed decides how bad the breach gets.
Watch for anomalies. Sudden traffic spikes, repeated authorisation failures, one caller walking through sequential IDs.
Alert on patterns, not single events. One failed login is normal. Failures spread across hundreds of accounts from a handful of addresses are not.
Connect alerts to people. Alerts need to reach someone who can act. A dashboard nobody checks isn’t security.
Prioritise by risk
You can’t fix everything at once. Focus on what matters most.
Identify sensitive endpoints. Payments, authentication and access to personal data get attention first.
Think like an attacker. What is valuable to steal? What damage could unauthorised access do? Protect those paths first.
Write down known gaps. A documented, accepted risk is better than an ignored one, and the list drives the next round of fixes.
Steps you can take today
- Export your route list and mark every endpoint that skips authentication.
- Pick your three most sensitive endpoints and test them as a second user.
- Turn on per-endpoint rate limits for login and password reset.
- Work through the OWASP API Security Top 10 checklist, one category a day.
- Put a free tool on live traffic and send its alerts to your team’s channel.
Enterprise-grade detection from $0
Cyron API Security detects attacks on REST, WebSocket, gRPC, Server-Sent Events and Socket.IO traffic, with dedicated detection for all 10 categories of the OWASP API Security Top 10 (2023), starting free, with published prices. No code changes.
Updated 1 October 2026: new title, a 30-day plan and a dated cost table with current plans and prices.