How much RAM does Caddy need? We measured: 40 MB idle
Caddy (web server / reverse proxy (automatic https)) used 40 MB of RAM across 1 process sitting idle with default configuration — measured by us, on real hardware, not copied from another blog. Runtime: Single Go binary
Effectively free to add in front of everything else you run — which is exactly what you should do.
What the vendors say
Caddy makes no meaningful RAM demands and does not pretend otherwise, but 'reverse proxy VPS' guides still start at 1 GB.
What changes under load
Idle is negligible. Memory rises with concurrent connections and TLS handshakes; certificate management itself is essentially free.
Methodology
Each app was started with its default configuration and an empty data directory, left to settle for 25–30 seconds, and confirmed alive with an HTTP request to its web interface. We then recorded the resident set size (RSS) of the app's entire process tree via ps. Apps were run directly on the host (no Docker), so numbers exclude container overhead (~10–30 MB with Docker).
A fresh minimal Ubuntu 24.04 VPS typically idles at roughly 200–300 MB RSS (kernel, systemd, sshd, journald). All 'fits on' verdicts below assume ~300 MB reserved for the OS.
Where to run it
A 512 MB instance from Hetzner, Vultr or DigitalOcean covers this app with the OS overhead included. Don't pay for RAM the measurements say you won't use.
Other apps we measured
File Browser (16 MB), Gotify (20 MB), ntfy (27 MB), PocketBase (31 MB), Navidrome (47 MB), Syncthing (57 MB), Prometheus (70 MB), MinIO (132 MB), Uptime Kuma (136 MB), Gitea (158 MB), Forgejo (173 MB), code-server (VS Code in the browser) (191 MB)