--- title: "Monitoring AWS Lambda & API Gateway | FourSight" description: "Detect cold-start latency spikes, throttling errors, and 5xx responses across serverless architectures." lang: en json-ld: | [ { "@context": "https://schema.org", "@type": "Article", "headline": "Monitoring AWS Lambda & API Gateway", "description": "Detect cold-start latency spikes, throttling errors, and 5xx responses across serverless architectures.", "author": { "@type": "Organization", "name": "FourSight" }, "publisher": { "@type": "Organization", "name": "FourSight" }, "url": "https://foursight.cloud/guides/monitoring-aws-lambda-apis", "mainEntityOfPage": "https://foursight.cloud/guides/monitoring-aws-lambda-apis", "datePublished": "2025-05-14", "dateModified": "2025-11-04", "wordCount": 1600 }, { "@context": "https://schema.org", "@type": "BreadcrumbList", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "Home", "item": "https://foursight.cloud" }, { "@type": "ListItem", "position": 2, "name": "Guides", "item": "https://foursight.cloud/guides" }, { "@type": "ListItem", "position": 3, "name": "Monitoring AWS Lambda & API Gateway", "item": "https://foursight.cloud/guides/monitoring-aws-lambda-apis" } ] } ] --- [FourSight ](/) [Features](/#features)[Pricing](/pricing)[Guides](/guides)[Glossary](/glossary)[FAQ](/faq) [Login](/auth)[Start free](/auth?signup=true) [Start free](/auth?signup=true) [All Guides](/guides) Platform-Specific Monitoring # Monitoring AWS Lambda & API Gateway Detect cold-start latency spikes, throttling errors, and 5xx responses across serverless architectures. 8 min read Guide Published May 14, 2025Updated Nov 4, 2025 ## Serverless Monitoring Challenges [AWS Lambda](/glossary/aws-lambda "Glossary: AWS Lambda")'s pay-per-invocation model is cost-effective, but its ephemeral nature makes monitoring harder. Functions cold-start, timeout, throttle, and fail in ways traditional monitoring doesn't catch. External HTTP monitoring from multiple regions is the most reliable way to verify your serverless APIs work end-to-end. ## Cold Start Impact on User Experience Lambda cold starts add 100ms to 10+ seconds of latency depending on runtime, package size, and VPC configuration. Monitor your [API Gateway](/glossary/api-gateway "Glossary: API Gateway") endpoints with response-time thresholds to catch cold-start regressions after deployments. ### Provisioned Concurrency Monitoring If you use provisioned concurrency to mitigate cold starts, monitor that it's working. A misconfigured provisioned concurrency setting can silently revert to on-demand, reintroducing cold starts. ### VPC Cold Starts Lambda functions in VPCs experience significantly longer cold starts due to ENI attachment. Monitor VPC-attached functions separately with higher timeout thresholds. ### Monitoring a Commercial SaaS? FourSight's free plan includes 10 commercial-safe monitors with multi-region validation — free forever, no card. [Start Monitoring Free](/auth?signup=true) ## Throttling Detection Lambda has concurrency limits per region (default 1000). When you hit limits, API Gateway returns 429 errors. Monitor for these with HTTP status code checks—throttling often happens during traffic spikes when you need reliability most. **💡** Request a concurrency limit increase before you need it. AWS takes 24–48 hours to process increases. Monitor your current concurrency usage and alert at 70% of your limit. ## API Gateway Health API Gateway can fail independently of your Lambda functions. Monitor your API's base URL and critical routes separately. Check for proper CORS headers if your frontend is a SPA—missing CORS headers produce confusing client-side errors. ## Multi-Region Failover Verification If you run a multi-region Lambda setup with Route 53 [failover](/glossary/failover "Glossary: failover"), use FourSight's [multi-region monitoring](/glossary/multi-region-monitoring "Glossary: multi-region monitoring") to verify that failover actually works. Test from regions closest to each deployment to ensure [DNS](/glossary/dns "Glossary: DNS") routing is correct. #### Related Guides [Monitoring Vercel & Next.js Deployments 8 min ](/guides/monitoring-vercel-deployments)[Monitoring Supabase-Backed Applications 11 min ](/guides/monitoring-supabase-applications)[Monitoring Cloudflare Workers & Pages 6 min ](/guides/monitoring-cloudflare-workers) #### Compare FourSight [vs UptimeRobot →](/compare/uptimerobot-alternative)[vs StatusCake →](/compare/statuscake-alternative)[vs Pingdom →](/compare/pingdom-alternative) 10 free commercial-safe monitors [View Pricing](/pricing) ## Protect Your SaaS Revenue Start monitoring in under 60 seconds. [Start Monitoring Free](/auth?signup=true)[View Pricing](/pricing) FourSight © 2026 [TetraCore](https://tetracorehq.com/). All rights reserved. FourSight is a TetraCore product — Bowling Green, Ohio. 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