Last updated: June 2026
Note: This is a part of our API Security series where we solve common developer queries in detail with how-to guides, common examples, code snippets and a ready to use security checklist. Feel free to check other articles on topics such as authentication methods, rate limiting, API monitoring and more.
Below are some common API security FAQs that serve as a valuable resource for understanding, implementing, and maintaining the robust security measures necessary to protect your APIs and the valuable data they handle.
1. How to handle when a token expires – generate and store new?
When an authentication token used with your API expires, the best practice is to generate a new token and update it in your application's authentication system.
This process often involves sending a request to the authentication server, such as an OAuth 2.0 token endpoint, with necessary credentials to obtain a fresh token.
The new token should then be securely stored and used for subsequent API requests. Make sure to handle token expiration gracefully in your application code by checking the token's expiration time and obtaining a new one before it expires to avoid disruptions in API access.
If you're integrating with several third-party APIs, this refresh logic has to be built and maintained separately for each provider's OAuth implementation. Knit handles OAuth 2.0 authentication and token refresh automatically across its supported integrations, so your application doesn't need to implement or monitor this logic per platform.
2. How often should I perform security audits and testing for my APIs?
Regular security audits and testing are crucial for maintaining API security. The right cadence depends on your organization's risk tolerance, regulatory requirements, and how quickly your API ecosystem changes — but in practice, it works best as two layers: continuous, automated checks that run with every API change or release, and periodic formal audits that go deeper into architecture, access controls, and threat modeling.
As a general guideline:
- Perform security audits during the initial API design phase, before new endpoints go live.
- Run automated security checks — such as dependency and vulnerability scans — as part of your development and integration pipeline, on every significant change.
- Schedule formal security assessments, including penetration tests, at least annually — or semi-annually for higher-risk or customer-facing APIs.
- Conduct additional audits in response to emerging threats, major provider API changes, or high-profile security incidents in your industry.
3. What should I do in case of a security breach involving my API?
Most established incident-response frameworks — including those published by AWS and IBM — describe a similar lifecycle: prepare, detect and analyze, contain, eradicate and recover, and apply lessons learned. In the unfortunate event of a security breach involving your API, that lifecycle translates into the following steps:
- Contain the breach: Isolate affected systems or resources to prevent further damage.
- Notify relevant parties: Inform your internal security team, management, and legal counsel.
- Assess the scope: Determine the extent of the breach, what data may have been compromised, and how the breach occurred.
- Mitigate the issue: Address the security vulnerability or weakness that led to the breach. Patch any vulnerabilities and secure access points.
- Notify affected parties: Depending on data protection laws and regulations, you may need to notify affected customers or users about the breach.
- Enhance security: Review and strengthen your API security measures to prevent future breaches. Update security policies and train your team on security best practices.
- Cooperate with authorities: If required by law, cooperate with law enforcement agencies or data protection authorities during investigations.
- Communicate ethically: Maintain clear and transparent communication with stakeholders, including affected parties, throughout the incident response process.
Remember, having a well-documented incident response plan in place beforehand can greatly streamline your actions in case of a security breach involving your API.
4. How can I monitor and log API activity for security purposes?
Monitoring and logging API activity is essential for security. To achieve this, consider implementing the following:
- Utilize logging libraries: Use logging libraries or frameworks in your application code to record API interactions, including request details, response data, timestamps, and client information.
- Leverage API gateways: API gateways often provide built-in logging and monitoring features. They can capture data like request/response payloads, error codes, and client IPs.
- Utilize third-party tools: Explore security information and event management (SIEM) solutions, log analysis tools, or dedicated API monitoring services to centralize and analyze API logs.
- Set up alerts: Configure alerts and notifications based on predefined security thresholds, such as unusual request patterns, high error rates, or suspicious activities, to take immediate action when necessary.
- Structure and retain your logs: Use structured (JSON) logging so logs can be filtered and queried programmatically, mask or exclude sensitive fields such as tokens and personal data before they're written, and define a retention window — a common guideline is at least 30 days of readily-searchable storage plus longer-term archival for audits and incident investigations.
For example – Knit has a dedicated Logs and Issues page where the status of each API call and webhook for all your integrated accounts is available for a quick review on a single page. Knit continuously monitors all integrations and sends you automated alerts whenever a security threshold is reached.
[image: existing screenshot of Knit's Logs and Issues page — unchanged]
5. What is the best practice for API token expiration?
There's no single lifetime that applies to every API, but Google's Apigee team publishes a widely-cited starting point: configure access tokens to expire after around 30 minutes and refresh tokens after around 24 hours, then adjust both based on your application's security and usability needs. In practice, lifetimes vary a lot by provider — some issue access tokens valid for hours, others for days, and refresh tokens can range from a day to several months — so always check the specific API's documentation rather than assuming a default. Shorter access-token lifetimes limit how long a leaked token stays useful, while longer refresh-token lifetimes reduce how often users have to re-authenticate. If you're managing this across several integrations, Knit issues and refreshes OAuth tokens automatically for its supported platforms, so each provider's specific token lifetime is handled for you rather than tracked manually.
6. Is an expired API token a 401 or 403 error?
An expired API token should return a 401 Unauthorized response, not 403 Forbidden. The distinction matters for how your application handles the error: 401 means the credentials provided — including an expired or invalid token — aren't sufficient to authenticate the request at all, while 403 means the credentials are valid but the authenticated user or application doesn't have permission for that specific action. On a 401, the correct response is typically to refresh the token and retry the request; a 403 usually signals a permissions or scope issue that refreshing a token won't fix. Not every API follows this convention strictly, so it's worth checking a given provider's documentation, but 401 is the technically correct code for an expired token.
7. What should be part of an API security checklist?
A practical API security checklist covers both how requests are authenticated and how the API behaves once a request is inside the system. At minimum, it should include: using OAuth 2.0 or another modern authentication standard with appropriately short-lived tokens, enforcing rate limiting and throttling to prevent abuse, validating and sanitizing all input, encrypting data in transit and at rest, logging and monitoring API activity with alerts for anomalies, and maintaining a documented incident response plan. For a more detailed, ready-to-use checklist with examples, see our API Security 101 guide.
8. How does Knit help secure API integrations across multiple platforms?
Knit reduces API security risk by acting as a single, consistently-secured layer between your application and the HRIS, ATS, CRM, and other platforms it supports. Instead of your team building and maintaining separate authentication, token-refresh, and data-handling logic for each connected platform — each with its own security model — Knit handles OAuth flows, token refresh, and credential storage centrally, and normalizes data from every integration into a consistent format. Knit also provides a dedicated Logs and Issues dashboard so you can review the status of every API call and webhook across your integrated accounts from one place, with automated alerts when a security threshold is reached. For teams integrating with many third-party APIs, this consolidates what would otherwise be dozens of separate security surfaces into one that Knit maintains and monitors.
