111 posts · writing since 2023
Notes on backend systems, cloud infra & life.
Field notes on Java, Rust, and the Cloudflare developer platform — written by a backend engineer, for backend engineers.
Latest
- 01 Your Site Is Down Under a DDoS? Find Out Which Layer Broke First New security· Oct 18, 2026
- 02 Astro, VoidZero, and now Deno: Cloudflare is buying up the frontend toolchain. What should developers do? cloudflare· Oct 11, 2026
- 03 Cloudflare cf CLI: Getting started and migrating from Wrangler cloudflare· Oct 7, 2026
- 04 Shopify Theme Development: Buy, Customize, or Build Your Own? Shopify· Oct 4, 2026
- 05 Choosing a Shopify App Stack: Official Template, Hybrid, or Custom Shopify· Oct 4, 2026
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Choosing Between Shopify Online and Offline Access Tokens
Choose Shopify Admin API tokens by permission boundary, not by whether a request starts in a browser. Covers staff access, background jobs, expiring offline tokens, and safe refresh.
How to Diagnose Slow NestJS Endpoints and Find Performance Bottlenecks
Use request traces, CPU profiles, event-loop delay, and connection-pool metrics to diagnose slow NestJS endpoints. Locate bottlenecks in DTO conversion, serialization, queries, and queueing, then verify improvements with load tests.
How to Fix Cloudflare Error 521: Don't Clear the Cache, Trace the Path
Cloudflare Error 521 (Web server is down) isn't fixed by clearing the cache — it means your origin refused Cloudflare's connection. This guide walks the path from web service and listening ports through firewalls / WAF and SSL/TLS ports to load balancers, plus a ready-to-send support ticket template.