Fly.io vs Spider Cloud

The two overlap only in that both surface inside agent stacks, but the capabilities diverge hard. Spider Cloud is a data-acquisition layer: one POST returns a rendered page as markdown, JSON, HTML, or text; crawl streams whole sites back as JSONL as each page finishes; a search endpoint returns SERP results, scraped pages, and AI extraction in one call. Its moat is rendering and anti-blocking — scripts run, lazy images load, infinite scroll completes, and Unblocker handles CAPTCHAs, bot walls, and geo checks with retries. Browser Cloud gives full stealth browser sessions, plus AI commands (Act, Extract, Observe) over a WebSocket mid-session, and a provider router lets you route requests to outside providers on your own keys. Fly.io is a compute layer: Sprites are hardware-isolated Linux VMs that checkpoint automatically so coding agents (Claude, Codex, Gemini) resume after sleep; Machines boot sub-second across 18+ regions; a Sprite Block Device (private beta) offers up to 100GB object-storage-backed disk; Sprites Connectors tie in GitHub, Slack, and OpenRouter. Fly.io's angle is safe execution of untrusted code with egress control and a clean baseline per request. One gets you the web; the other gets you a machine. Neither substitutes for the other.

Spider Cloud's freemium model actually splits into two motions: a flat-rate Unlimited tier where concurrency — not per-request metering — is the constraint, and pay-as-you-go for flexible usage. Two cost traps are documented and worth budgeting for: residential/ISP proxy pools and AI extraction bill separately from base request pricing, and geo-targeting isn't available on Unlimited, so geo-fenced crawls stay on pay-as-you-go. Also plan for HTTP 429 handling, since Unlimited queues nothing server-side. Fly.io bills per second of active CPU and memory, and the meter hits zero when nothing is running — which is the headline economic advantage for intermittent agent workloads. Storage tiers separately as hot or cold, and the Sprite Block Device is in private beta so its eventual pricing isn't settled. The pricing philosophies are opposite: Spider Cloud's cost scales with how much web you pull; Fly.io's scales with how long your code runs. A heavy RAG ingestion month blows up Spider Cloud's bill and barely touches Fly.io's; a spike of constant high CPU runs the other way — Fly.io's own guidance flags that pattern as potentially cheaper on reserved instances elsewhere.