Application Programming Interfaces (APIs) are digital highways that connect users, partners, and applications to core services across different networks. As APIs’ role continues to expand in data exchange and system interconnectivity, they become more attractive targets for cybercriminals looking to gain unauthorized access, exfiltrate data, or disrupt services.
As organizations scale, so does the complexity of their API environments—across mobile apps, software integrations, cloud platforms, and IoT devices—which increases exposure to security gaps. Even unintentional misconfigurations, such as weak authentication or insecure data transmission, can initiate devastating breaches.
This calls for a proactive stance that combines best practices around strong authentication, strategic rate limiting, strict input validation, and continuous security monitoring. In this blog, we will explore seven best practices that will help you to strengthen your API endpoint security. By prioritizing these measures, you will help to protect your valuable data, maintain the trust of your users, and keep your services resilient against evolving cyber threats.
7 Best Practices for API Endpoint Security
Application programming interfaces (APIs) are a natural weak point because they connect users who may work anywhere in the world with your primary network. Sensitive information passes through the interface and protocol that’s shared between the user and the back end. Most organizations suffer some kind of API endpoint security breach each year. Some are unintentional or benign, but many are malicious.
Implement these seven best practices to secure your API endpoints.
1. Authentication and Authorization
Authentication and authorization issue a token that users must have before gaining access, ensuring that every user of your API infrastructure authenticates with the API endpoint. One of the most popular methods is the Challenge Handshake Authentication Protocol (CHAP). With CHAP, you generate an authentication token, which is then hashed and matched with the hashed tokens in the database and the API server. Successful authentication is only possible if there’s a match with the input token in the database.
This forms a basic form of authentication with more advanced layers, such as JSON web tokens (JWTs) and OAuth, which provide a complete authentication infrastructure to your system.
2. TLS/SSL Encryption
TLS/SSL encryption secures your endpoint with a handshake-based encryption method such as SSL. This can prevent third parties from listening to your API requests and retrieving sensitive data.
You can integrate with existing Single Sign-On (SSO) providers by using OpenAuth2 with OpenID Connect. It reduces the risk of sensitive data exposure and users can verify themselves with a trusted third party by means of token exchange to get access to resources. OAuth2 can be used in both stateless and stateful modes.
3. Rate Limiting and Throttling
Rate limiting is a security method that limits the number of requests a user can make. Similarly, throttling restricts the number of requests a user can make in a given period (e.g., per day).
You can do this to prevent a malicious third party from mounting denial-of-service attacks on your API infrastructure. You can set it up on your back end by writing the necessary logic, or you can use something from a third-party, such as SentinelOne’s Singularity Endpoint Solution.
4. Input Validation and Sanitization
When you send a request to an API endpoint, your input is validated and sanitized to prevent code injection or malicious entries from being processed. This prevents possible denial-of-service or backdoor attacks on your API system.
You can secure your API endpoint using sanitization by using an external library such as nh3 for Python. It seamlessly sanitizes your input data by using the function nh3.clean (“your input data here”). You can use regex for basic input validation, or you can consider input sanitation for more advanced validation.
5. Regular Security Audits and Penetration Testing
Regular security audits and penetration testing by a trusted cybersecurity company are a great way to do security audits. Audits test weaknesses and vulnerabilities in your system. A security auditor scans your complete API infrastructure for any possible vulnerabilities and performs penetration testing on suspected weak points to test your API infrastructure.
Regular security audits can bolster your API system’s security and performance. With an ISO 27001 cybersecurity audit, for example, a security auditor will review your organization’s security and verify that it aligns with the ISO 27001 security best practices.
6. API Gateways
API gateways are cloud services or external API management providers that handle your API. Using an API gateway is a secure way to manage your API endpoint because the service provider takes care of a lot of the security measures for you. API gateways connect your back end with their secure API endpoint. This allows your API infrastructure to go online fast without requiring you to manually configure the complete API endpoint.
Amazon AWS API Gateway is a popular API gateway and is widely considered to be the industry’s best.
7. Reverse Proxy Servers
Reverse proxy servers act as intermediaries between the API endpoint and the API back end. They usually forward traffic from the endpoint and return the response generated by the API to the user or front end. This is simple to set up as it only requires a virtual server instance from your cloud provider.
You can set up the instance to act as a reverse proxy instance by using reverse proxy software such as nginx, which can also help with load balancing. Therefore, reverse proxies add a layer of security and act as a buffer between your users and your API application.
A Holistic API Endpoint Security Solution
SentinelOne offers API endpoint security solutions that provide visibility into your data flows and an overall view of your company’s security posture. Following these seven best practices helps build robust protection. Schedule a demo to see how SentinelOne can implement AP endpoint security for your organization.
Conclusion
Securing API endpoints is a process. It requires being vigilant, adaptive, and strongly focused on risk prevention. You can substantially increase the security of your API by following these best practices, from solid authentication to regular audits. Long-term security posture can be easily maintained.
Remember, threats are in a rapid state of evolution. Therefore, regular training, updating, and monitoring are essential to making it through in the long run. Whether small or large, building a resilient API framework for your project or enterprise is pertinent. Resilience keeps customer faith intact and critical data safe and sound. Integrate advanced solutions, such as those provided by SentinelOne, to bolster your defenses. You can confidently run and scale your APIs in today’s digital environment. Stay prepared, and keep your systems secure against evolving threats.
FAQS
API endpoint security focuses on protecting each specific URL or route in an API that clients use to talk to your back end. It covers who can call that endpoint, how requests are encrypted, and checks on input to stop attacks.
You guard endpoints with strong auth, TLS/SSL, input validation, and traffic controls so only valid calls reach your services.
API endpoints are the doorways into your systems. If they’re open or weakly protected, attackers can slip in malicious requests, steal data, or overwhelm your services. Locking down endpoints stops unauthorized access, keeps data private in transit, and prevents attackers from exploiting flaws like injections or broken auth, so your apps run safely.
Attackers often use broken authentication or authorization to gain access, injection attacks (SQL, command, or XML) to manipulate back ends, denial-of-service floods to crash APIs, and man-in-the-middle eavesdropping on unencrypted traffic.
Misconfigurations—like exposing debug endpoints—brute-force logins, and excessive data exposure rounds out the usual suspects.
TLS/SSL wraps API traffic in an encrypted tunnel so data, credentials, and tokens can’t be read or altered mid-stream. When clients and servers handshake, they verify each other’s identity and exchange keys for encryption.
That means API keys or passwords never travel in clear text, thwarting eavesdropping and man-in-the-middle attacks.
API gateways act as the single entry point for your APIs. They enforce authentication and authorization, apply rate limiting and throttling, inspect and validate requests, and centralize logging. Gateways can block known bad patterns, offload TLS termination, and route calls to proper services—so you don’t have to build those guards into every endpoint.
API endpoint security zeroes in on each path and method—who calls it, how inputs are checked, and how traffic is protected. General API security covers the broader picture—architecture design, secure coding, and overall platform defenses. Endpoints are one layer where you apply the detailed controls that enforce the bigger API security strategy.
Rate limiting caps how many calls a client can make in a time frame, stopping brute-force, DoS, or credential stuffing attacks before they overwhelm your services. TLS ensures each API request is encrypted and authenticated, so even if attackers hammer your endpoint, they can’t spy on or tamper with the data in flight.
SentinelOne’s Singularity platform integrates endpoint and workload telemetry with your API gateway or SIEM. It enriches access logs with threat verdicts, flags anomalous client behaviors, and can trigger one-click actions—like blocking IPs or forcing token revocations. With its AI-driven detection, you spot API abuse and misconfigs fast and take automated steps to lock down affected endpoints.