Buglyst Blog
Learn to debug under pressure.
Playbooks for fast pattern recognition, guides for the full investigation, and articles for the engineering judgment around the edges.
17 playbooks · 509 guides · 95 articles · 12 linked practice labs ·skip to practice
Fast pattern recognition for the production failures engineers see most often.
17 playbooks
Debugging Env Var Issues
A concise checklist for incidents where local works but CI, staging, or production changes behavior.
Debugging Cache Stampedes
How to recognize and contain request spikes when cached data expires.
Debugging CORS Origin Bugs
A practical way to inspect origin parsing, credentials, and header behavior.
Debugging Retry Bugs
Retry issues often hide the first failure and create duplicate work.
Debugging Timezone Bugs
Time bugs usually live at day boundaries, DST changes, and unit conversions.
Debugging Pagination Bugs
Pagination bugs hide in boundary math, cursor reuse, and new records arriving between pages.
Structured investigations for the failure modes engineers meet in real systems.
Stripe Webhook Signature Verification Failed: A Debugging Guide
Diagnose and fix Stripe webhook signature verification failures. Covers common causes like clock drift, wrong signing secret, and raw body mismatches.
OpenAI API 429 Rate Limit Error: Diagnosis and Fixes
A focused guide on diagnosing and resolving HTTP 429 rate limit errors from the OpenAI API, covering root causes, retry strategies, and monitoring.
SendGrid Email Not Delivered: Diagnosing Silent Delivery Failures
A practical guide to diagnosing why SendGrid emails are accepted but never arrive, covering SPF/DKIM, bounces, suppression lists, and IP reputation.
Debugging LangChain Chain Output Errors: A Practical Guide
A hands-on guide to debugging LangChain chain output errors, covering common causes, quick diagnosis, and fixes.
Firebase Security Rules Blocking Requests: Debugging Guide
A practical guide to debugging Firebase Security Rules that unexpectedly deny requests. Covers simulator pitfalls, missing auth tokens, and rule ordering issues.
Debugging Firebase Realtime Database Offline Sync Failures
A focused guide to diagnosing and fixing when Firebase Realtime Database fails to sync data while offline, covering local state mismatches, conflict resolution, and connectivity edge cases.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Tracking Down a 200 MB Leak with Python Memory Profilers
A production API was silently leaking 200 MB of RAM every hour. Here's how memory profilers found the culprit—a forgotten NumPy array reference—and how you can apply the same techniques.
Reading CPU Flame Graphs: What the Hot Colors Actually Tell You
Flame graphs are everywhere, but most engineers read them wrong. Here's how to identify real bottlenecks, avoid common misinterpretations, and turn profile data into actionable fixes.
When Logs Lie: The Gaps Between What You Log and What Actually Happened
Logs are the first thing we reach for during an incident. But they can be misleading, incomplete, or outright wrong. Here's when to trust them and when not to.
Adding Observability to a 500K-Line Monolith Without a Rewrite
Adding structured logging, distributed tracing, and metrics to a legacy monolith without a full rewrite. Real code examples and a war story from a 500K-line codebase.
Distributed Tracing: Following a Single Request Across Microservices
Distributed tracing lets you follow a request as it hops across services. I'll show you how trace context propagates, why sampling matters, and how tracing helped us debug a 5-second latency spike in production.
Structured Logging in JSON: Fields, Schemas, and Pitfalls from Production
A practical guide to designing JSON log schemas that are queryable, consistent, and actually useful in production — with field recommendations and a war story.