How Compiler Explorer's AWS Infrastructure Works in 2026
An inside look at Compiler Explorer's AWS setup: CloudFront, spot instances, EFS/CEFS storage, and its nightly compiler build pipeline.
A new technical write-up details how Compiler Explorer's cloud architecture has evolved on AWS. Requests pass through CloudFront and WAF rate limiting before hitting a single Application Load Balancer that routes traffic to separate fleets for production, beta, staging, Windows/MSVC, ARM (Graviton), and GPU instances. Each fleet uses blue-green deployment, and most production capacity runs on spot instances for significant cost savings.
The hardest engineering problem is serving roughly 6,000 compiler builds across 93 languages, none of which are ever deleted. SquashFS images mounted via loopback devices on EFS solved NFS latency issues, and a newer content-addressed system called CEFS cut the number of mounted images from 2,182 to 121, dropped boot time from 50 to 20 seconds, and reduced total storage from 3.9TB to 2.2TB.
The team also builds 94 compilers from scratch nightly, including GCC and Clang trunk, using self-hosted GitHub Actions runners on EC2. A still-incomplete component called CE Router aims to decouple request handling from compilation by using DynamoDB, SQS, and API Gateway WebSockets. The piece offers a concrete case study in running a large-scale, cost-constrained open-source service on public cloud infrastructure.