Blaxel vs Fly.io Sprites
Answer in brief
Choose Blaxel for always-available agents that sit idle most of the time and need near-instant resume; choose Fly.io Sprites for long-running, stateful agent computers that should cost nothing while idle. Blaxel uses MicroVM isolation; Fly.io Sprites uses MicroVM isolation.
Blaxel vs Fly.io Sprites at a glance
| Attribute | Blaxel | Fly.io Sprites |
|---|---|---|
| What it is | Perpetual microVM sandboxes for AI agents that drop to standby when idle and resume with memory intact, plus volumes, batch jobs and MCP hosting. | Persistent, hardware-isolated Linux computers for AI agents with a durable 100 GB disk, checkpoints, and no compute charges while idle. |
| Isolation | Hardware-isolated microVM per sandbox; root filesystem held in memory; hypervisor not named | Dedicated microVM with hardware-level isolation (Fly docs); reported to be Firecracker-based |
| Open source | No (SDKs MIT / Apache-2.0) | No (SDKs MIT) |
| Self-host / BYOC | No / Yes | No / No |
| SDKs | TypeScript, Python, Go | JavaScript/TypeScript, Go, Python, Elixir |
| Cold start (vendor claim) | Resume from standby in under 25 ms (vendor claim); new sandboxes in under a second | Warm wake 100–500 ms with processes preserved; cold wake 1–2 s (vendor docs) |
| Max session | Designed to persist indefinitely in standby; workloads from seconds to multiple days | No lifetime limit — a Sprite persists until destroyed and sleeps after ~30 s idle |
| Persistence | Automatic standby after ~5–15 s idle snapshots memory, processes and filesystem; forkable snapshots; volumes and a shared Agent Drive | 100 GB durable disk per Sprite that survives sleep; copy-on-write checkpoints (~1 s) with restore; memory preserved on warm pause |
| GPU | Not documented | No GPU option documented |
| Networking | Preview URLs with stable names; outbound via proxy, firewall rules or dedicated egress IPs; custom domains | HTTPS URL per Sprite (org-private by default); outbound open by default with optional DNS-based domain allow/deny policy; connectors broker API credentials |
| Pricing | Per second on allocated memory: $0.0000115 per GB-second (~$0.041/GB-hour) while active; standby billed as snapshot storage ($0.20/GB-month) | Per second, compute only while active: $0.0385 per CPU-hour + $0.021875 per GB-hour memory; storage billed while idle |
| Compliance | SOC 2, ISO 27001, GDPR, CCPA; HIPAA with BAA as a paid add-on | Fly.io is SOC 2 Type 2; HIPAA BAA and DPA available (company-wide) |
| Best for | Always-available agents that sit idle most of the time and need near-instant resume | Long-running, stateful agent computers that should cost nothing while idle |
Verified November 8, 2026 from each provider’s documentation. Cold-start figures are vendor claims, not our measurements.
Which should you choose?
Choose Blaxel if…
- You want a persistent sandbox per user without paying for idle compute
- You need very fast resume from standby
- You want Go as well as Python and TypeScript SDKs
Choose Fly.io Sprites if…
- You want a persistent computer per agent or per user
- Your agents are idle most of the time and you want to pay only for active compute
- You want fast checkpoints and rollback
- You want Elixir or Go SDKs
Both are worth piloting with your own image and region. See the full Blaxel profile and Fly.io Sprites profile, or the complete comparison.
Frequently asked questions
Is Blaxel or Fly.io Sprites better for AI agents?
Neither is better for every workload. Blaxel is best for always-available agents that sit idle most of the time and need near-instant resume. Fly.io Sprites is best for long-running, stateful agent computers that should cost nothing while idle.
Which is open source, Blaxel or Fly.io Sprites?
Neither is open source.
How do Blaxel and Fly.io Sprites isolate code?
Blaxel: Hardware-isolated microVM per sandbox; root filesystem held in memory; hypervisor not named. Fly.io Sprites: Dedicated microVM with hardware-level isolation (Fly docs); reported to be Firecracker-based.
Sources
Cite this page
Agent Sandboxes. (2026). Blaxel vs Fly.io Sprites. agentsandboxes.org. Last reviewed November 8, 2026. https://agentsandboxes.org/compare/blaxel-vs-fly-sprites/
Found an error or a missing sandbox? Submit a correction — every entry links to the sources it relies on.