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.
3 playbooks in Backend & APIs
Debugging Retry Bugs
Retry issues often hide the first failure and create duplicate work.
Debugging Idempotency Bugs
How to debug duplicate writes when clients, webhooks, or workers retry after ambiguous failures.
Debugging Payment Races
How to reason about duplicate charges, concurrent refunds, and payment workflow compensation.
Structured investigations for the failure modes engineers meet in real systems.
GraphQL Subscription WebSocket Not Receiving Events
A step-by-step debugging guide for when GraphQL subscriptions fail silently over WebSocket—no events, no errors, just silence.
Debugging Apollo Federation Subgraph Errors: A Field Guide
A practical guide to diagnosing and resolving errors from Apollo Federation subgraphs, including type resolution failures, entity lookup issues, and gateway-subgraph communication problems.
Socket.IO Client Not Reconnecting: Debugging Reconnection Failures
This guide covers why a Socket.IO client fails to reconnect, including transport downgrade, middleware blocking, and client-side timeout misconfiguration.
Twilio SMS Delivery Failure Debugging
Step-by-step guide to diagnose Twilio SMS delivery failures: check logs, error codes, carrier issues, and fix patterns.
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.
Long-form thinking on debugging habits, observability, and the systems around the bug.
Debugging Third-Party API Issues: A Systematic Approach
A practical guide to diagnosing and fixing third-party API integration problems, with real-world examples and a step-by-step debugging framework.
Debugging Webhook Delivery Failures: What the Logs Don't Tell You
HTTP 200 doesn't mean your webhook was processed. A practical guide to the network and middleware layers that silently drop webhooks.
Debugging HTTP Headers with curl: From Basic Flags to Packet-Level Inspection
A practical guide to inspecting HTTP request and response headers with curl, covering basic flags, debugging tricky issues, and understanding what your headers are really doing.
Debugging WebSocket Real-Time Features: Packet Loss, Reconnect Storms, and Silent Failures
WebSocket debugging goes beyond console.log. I cover packet capture with tcpdump, reconnect backoff strategies, and a war story about a silent failure that took down a production chat feature.
Rest API Design Mistakes That Inject Bugs Into Your System
Most API bugs aren't in the implementation—they're baked into the contract. Here are the design errors I've seen cause the most production incidents.
Idempotency Keys: The Safety Net Your Payment API Needs
How idempotency keys prevent double charges, lost refunds, and data corruption in payment APIs. With real-world examples and edge cases you haven't considered.