Email and newsletters

Spike alternatives

2 open-source projects that already do this job. Free to use - not free to run, which is what the numbers on the right are for.

The full assessment →

The projects

Foundry376/Mailspring17,726GPL-3.0A fast, cross‑platform desktop email client with account sync, threading, and search.Open on GitHub cloudflare/agentic-inbox6,757Apache-2.0A self‑hosted email client powered by an AI agent, built to run on Cloudflare Workers.Open on GitHub

What you give up either way

Hosted custom email domains and email hosting
Shared inbox/teamspaces at production scale (collaboration workflows)
Integrated video & audio calls, collaborative docs, and SSO
Mobile/desktop native apps and cross-device polished clients
Spike AI feed throttling, enterprise integrations, and recording features

An open-source project doing the core job proves a replacement is possible. It does not prove it matches Spike, and it does not prove anyone has run it for a month. How we decide.