How We Built a Serverless Image CDN: Lessons from Production at Clicker Cloud (2026)

How We Built a Serverless Image CDN: Lessons from Production at Clicker Cloud (2026)

Hook: In 2026, image delivery mistakes cost both performance and cloud budgets. Our serverless image CDN reduced latency and cut per-image spend by 42% — here’s the how and why.

Context and motivation

We migrated a high-traffic editorial property to a serverless image CDN to remove a brittle origin cache and accelerate format negotiation at the edge. The goal: automated format selection (JPEG/WebP/AVIF), client-aware quality, and cost predictability.

Key technical building blocks

• Edge format negotiation: client hints + AVIF fallback. The JPEG vs WebP vs AVIF tradeoffs shaped our pipeline — practical guidance is available in the 2026 comparison to quantify both decode cost and payload size (jpeg.top).
• Layered caching: global CDN + regional compute-adjacent caches for transformation hot paths. The layered cache design was inspired by modern inventory & caching patterns (cartradewebsite.com).
• Small tools for the pipeline: we adopted a curated set of lightweight tools from the 2026 publishing tech roundup to decrease build complexity and improve deploy times (writings.life).

Operational learnings

Three operational pillars made this sustainable:

1. Idempotent transforms for retries; transforms declare inputs and outputs - no stateful side effects.
2. Cost observability: per-transform cost tagging surfaced unexpectedly expensive operations, enabling granular budget controls. Teams today are looking at cashback and committed credit strategies to offset burst costs (moneys.pro).
3. Fail-open fallbacks: when edge transforms fail, serve original or a pre-warmed format to preserve UX.

Performance and cost metrics

Across three months we measured:

• Median transfer size down by 38%
• First contentful paint improved by 0.45s on mobile
• Per-request compute cost down by 26% after tuning cache TTLs

How to adopt this pattern without a full rewrite

Start with an edge-aware image proxy configured as a sidecar to your CDN. Use format negotiation and a small warm pool of transformed images for highest-traffic assets. For teams selling physical products or running deal sites, inventory and pop-up strategies influence cache churn — see advanced inventory playbooks for deal sites and microbrands (cheapdiscount.sale).

Related operational reading

• Image formats and decoding costs — jpeg.top
• Layered caching fundamentals — cartradewebsite.com
• Small tools to reduce pipeline friction — writings.life
• Cost optimization and reward strategies — moneys.pro
• Deal-site inventory churn patterns — cheapdiscount.sale

Author: Jonah Park — Infrastructure Engineer, Clicker Cloud. I built and ran the image CDN migration and authored our cost observability dashboards.