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Fly.io vs Sst

Fly.io scores higher on the AgentReady, 53/100 against 44/100. They differ on 8 of the 41 signals. Which ones decides whether an agent can adopt them without a person watching.

What each one is

Fly.io. Fly.io provides real hardware-isolated Linux computers (called Sprites and Machines) for agents, evals, and tools, with a pay-as-you-go model where billing goes to zero when not in use.

Sst. SST is a framework that makes it easy to build modern full-stack applications on your own infrastructure.

Where Fly.io is ahead

Fly.io passes mcp discoverable, and Sst does not. That is discover, whether an agent can find the product at all without being told it exists.

It also holds understand: pricing understandable. Sst misses it.

And on adopt, self-service signup and mcp integration available. Sst misses those.

Finally, on operate, agent compatibility verified. Sst misses it.

Where Sst is ahead

Sst passes llms-full.txt / full agent docs, and Fly.io does not. That is discover, whether an agent can find the product at all without being told it exists.

It also holds understand: structured api reference. Fly.io misses it.

And on adopt, agent-compatible signup flow. Fly.io misses it.

What neither does

Both fail clear product positioning, openapi / spec quality, authentication documented, request examples provided, response examples provided, errors and status codes documented, limits / constraints documented, no mandatory sales call, programmatic credential creation, free trial or free allowance, fast time to first request, copyable quickstart, structured, predictable output, machine-readable errors, retry behavior documented, idempotency support, rate-limit behavior predictable. If your agent needs any of those, you will be building it yourself either way.

Score, pillar by pillar

The AgentReady splits into four pillars, scored separately, because a product can be easy to find and still impossible to adopt.

Discover. Fly.io leads 80 to 73. Fly.io misses clear product positioning, llms-full.txt / full agent docs; Sst misses clear product positioning, mcp discoverable.

Understand. Sst leads 31 to 23. Fly.io misses structured api reference, openapi / spec quality, authentication documented, request examples provided, response examples provided, errors and status codes documented, limits / constraints documented; Sst misses openapi / spec quality, authentication documented, pricing understandable, request examples provided, response examples provided, errors and status codes documented, limits / constraints documented.

Adopt. Fly.io leads 55 to 38. Fly.io misses no mandatory sales call, agent-compatible signup flow, programmatic credential creation, free trial or free allowance, fast time to first request, copyable quickstart; Sst misses self-service signup, no mandatory sales call, programmatic credential creation, free trial or free allowance, fast time to first request, copyable quickstart, mcp integration available.

Operate is whether an agent can run against it in production and recover when a call fails. Fly.io leads 53 to 35. Fly.io misses structured, predictable output, machine-readable errors, retry behavior documented, idempotency support, rate-limit behavior predictable; Sst misses structured, predictable output, machine-readable errors, retry behavior documented, idempotency support, rate-limit behavior predictable, agent compatibility verified.

Pricing

Fly.io starts at $29/mo. Sst does not publish one.

Signal by signal

Which to pick

Fly.io clears more of the signals an agent needs, so it is the safer default for unattended use. Full profiles: Fly.io and Sst. Alternatives to each: Fly.io, Sst.

An agent can fetch this as data: POST /v1/compare {"slugs": ["fly", "sst"]}