CrabTalk vs Sprites.
Persistent Linux computers on Fly.io
Sprites are persistent Linux computers for agents, with filesystems, checkpoints, HTTP URLs and automatic idle behavior. CrabTalk hosts defined SQL tools whose state and per-call budgets are independent of a general-purpose machine.
Which fits your work?
CrabTalk
- A bounded operation shared across agents and applications
- Published tools or independent private templates
- Explicit per-call CPU, row and memory budgets
Sprites
- A persistent Linux workspace with installed tools
- Arbitrary code, services and repository operations
- Filesystem checkpoints and automatic wake on requests
Use both.
An agent inside a Sprite can call a CrabTalk tool over HTTP or MCP for an existing integration or shared result lookup. Keep the working repository and files in the Sprite when its persistent disk already meets the need.
Capabilities side by side.
| Capability | CrabTalk | Sprites |
|---|---|---|
| Execution unit | A defined tool call | Programs running in a persistent Linux computer |
| Memory accounting | Reserved budget, optionally lowered during the call | Actual memory usage while active |
| Persistent state | SQL records and values by key per service | Persistent filesystem and environment checkpoints |
| Idle behavior | No running guest instance between calls | Automatic idle state with preserved filesystem |
| Environment | Rust/Wasm with registered host APIs | Linux packages, files, commands and services |
| Network access | Declared destinations and host-managed service secrets | HTTP URLs and external-service Connectors |
| Reuse | Shared tools or deployable service copies | Persistent environments and filesystem checkpoint restore |
Maintain a working repository and a shared review index.
A persistent machine can keep the worktree. A separate index is useful only when other callers need stable queries over review records.
CrabTalk
- Choose or define SQL tools for the review index
- Perform repository work in the caller’s execution environment
- Record and query structured decisions through the service
Sprites
- Create a Sprite and install or obtain the repository tools
- Run the review commands in the persistent environment
- Keep results on disk or expose the required service on its URL
CrabTalk vs Sprites pricing.
CrabTalk
Callers pay a published tool’s price when it has one. Service owners pay runs, CPU, reserved memory-time and database rows, plus upstream provider usage. Memory is reserved per tool and can be lowered once for a smaller call.
Sprites
Sprites meters active CPU time and actual memory usage. Hot storage bills while the Sprite is awake; cold storage bills while the data is retained. Its published resource pricing is separate from Fly Machines instance pricing.
Estimate active resource usage and retained data. Sprites is outside the calculator; do not model its memory charge as a permanently reserved full-machine allocation.
Limits that affect the choice.
- CrabTalk tools have at most 100 ms CPU and 128 MiB memory, with a 60-second call chain. They cannot replace a general Linux workspace.
- Sprites already provides persistence, actual-memory billing and external-service Connectors. Those capabilities should be included when comparing state, cost and credential handling.
- A persistent filesystem is not automatically a shared service API. Build an API only when needed; keep files local when that already completes the task.
Questions about CrabTalk and Sprites.
Are Sprites ephemeral between runs?
No. They preserve a persistent filesystem and support checkpointing. Their idle lifecycle differs from a fresh Wasm tool instance.
Does smaller declared memory always make CrabTalk cheaper than a Sprite?
No. Sprites meters actual memory, while CrabTalk meters its reserved call budget. Compare the real workload, active time and storage instead of inferring a winner from nominal machine size.
Should I move an existing Sprite’s data into CrabTalk?
Only for a useful separate tool boundary. Keep an existing workspace and its files where they are when persistence and local commands already provide the required outcome.
Sources.
Checked .