Dropstone (site) is a runtime for intelligence that lets an AI assistant remember, learn, and act across tasks, evolving toward an always-on digital workforce. It runs on a freemium model: the free tier gives limited monthly usage, and paid plans start at $15/month (Pro, 6x more usage) up to $75+/month (Max, 5-10x more usage).
If you want more usage headroom without a subscription, or you'd rather self-host and pay nothing, here are three alternatives that offer a real free tier or are free entirely.
Comparison
| Product | Free tier | Starts at | Best for |
|---|---|---|---|
| Dropstone | Yes (limited usage) | $15/mo | An evolving AI assistant/workforce runtime |
| Statewave | Yes (self-hosted, free) | Not stated | Teams that want an open-source memory layer they control |
| Brain | Yes (open source) | Not stated | Developers who want a lightweight, hackable agent runtime |
| Inworld Runtime | Yes (On-Demand tier) | $25/mo | Production voice/AI apps needing a high-performance C++ runtime |
Statewave
Statewave (site) is an open-source memory runtime for production AI agents, released under Apache 2.0. It's self-hosted on Postgres and can be run locally with a single command — no account required. This suits teams that want memory infrastructure they own outright rather than a hosted subscription. No pricing is stated anywhere since it's free, open-source software; the tradeoff is you're responsible for hosting, scaling, and maintenance yourself, and there's no managed/paid tier described if you later want support.
Brain
Brain (site) is a small, fast, extensible agent runtime distributed as an open-source GitHub project under an MIT license. It fits developers who want a minimal, code-first runtime to build or embed into their own agent systems rather than a full managed product. There's no pricing information on the product itself — the free tier is simply "open source, use it freely." The limitation: as a young GitHub project (8 launch-day votes), documentation, stability, and long-term support may be thinner than a commercial offering.
Inworld Runtime
Inworld Runtime (site) is a C++ graph-based runtime built for production AI apps, aimed at engineers who want to spend less time on AI ops/plumbing and more on features. It defines AI logic as graphs, useful for streaming pipelines like voice-to-voice. It suits teams building high-concurrency, production-grade AI apps rather than hobby projects. The free On-Demand tier covers evaluation and prototyping (up to 70 minutes of TTS included); paid plans start at $25/month (Creator) and scale to $1,500/month (Growth). Limitation: the free tier's usage cap (70 min TTS) is modest for anything beyond prototyping.
How to choose
- Want zero cost and full control over your data and hosting: pick Statewave or Brain, both open source with no listed pricing.
- Want the lightest, most hackable codebase to extend yourself: pick Brain.
- Need a memory layer specifically, self-hosted on Postgres: pick Statewave.
- Building a production voice or streaming AI app and need a performant graph-based runtime, with room to pay later: pick Inworld Runtime.
- Want an assistant-style runtime that grows into automated tasks and don't mind a low-cost paid tier: stick with Dropstone at $15/month.
FAQ
Is Dropstone's free tier enough for regular use? It offers limited monthly usage, so heavy users will likely need the $15/month Pro tier or higher.
Are Statewave and Brain really free, or freemium? Both are fully open-source (Apache 2.0 and MIT respectively) with no pricing stated, meaning they're free to self-host.
Which alternative is best for production apps rather than prototypes? Inworld Runtime is built for production AI apps, though its free tier is capped at 70 minutes of TTS for evaluation purposes.