Comparison
Rails Agent vs ActiveAgent
ActiveAgent brings ActionMailer ergonomics to LLM calls. Rails Agent goes further: an engine mounted at `/agents`, a cloud runtime, and a full dashboard for traces, evals and deploys.
What they share
A love of Rails idioms. Both feel like `ActionMailer` for AI. Both are MIT-licensed. Both target Ruby ≥ 3.2 and Rails ≥ 7.1.
Where Rails Agent goes further
- Mounted engine with signup, dashboard and chat at `/agents`
- Managed cloud runtime on Vercel — no infra to set up
- Streaming, tool calls, memory, and human-in-the-loop as first-class DSL
- Traces, cost tracking and evals out of the box
- Vibe-coding chat that scaffolds agents directly into your repo via PRs
Sample DSL
class Concierge < RailsAgents::Base
model "gpt-4o-mini"
tool :lookup_order, using: OrdersTool
memory :thread, ttl: 1.hour
instructions <<~PROMPT
You are a support concierge for a Rails-powered SaaS.
PROMPT
end