# Sprites (Fly.io)

Official pricing: https://fly.io/pricing  
Category: agent-sandbox · Isolation: firecracker

## Pricing regimes (raw)

- **Sprite, billed on actual CPU time + actual memory while awake** (resource): $0.0385/vCPU-h, $0.021875/GiB-h

## Features

Yes: snapshots, pause/resume, persistent disk, whole disk survives a stop, idle auto-stop, ≥24 h sessions, custom image (Docker or snapshot), start from your own snapshot, full VM (own kernel), Docker inside, root, preinstalled agents, HTTPS preview URLs, egress allowlist, open internet, SOC 2, HIPAA, SSO, Python, Node.js, Go, Rust, Java, credential injection, HTTP method/path egress rules, wake on request, MCP server, automatic snapshots, snapshots on demand, gVisor or VM (no shared kernel), inbound access rules, firewall inside (nftables), secret proxy, secret proxy for any API, FUSE mounts, kernel features (eBPF, mounts, cgroups)

No: memory snapshots, fork/clone, volumes, your own Docker/OCI image, nested virtualization, systemd, browser, desktop GUI, computer-use API, code interpreter, browser + desktop control, anti-bot stealth, CAPTCHA solving, residential IPs, SSH, public IPv4, raw TCP inbound, static egress IP, private networking, self-hosting, BYOC, open source, GPU, arm64, Windows, macOS, GPU desktop, live resize, live fork (no pause), memory fork, webhooks, EU data residency, usage per sandbox (API), agent harness API, hosted agent API (their own agent), extra volumes, shared volumes

Unknown: everything else. Evidence (source + quote) per feature: https://battleships.dev/data/providers/sprites.json → feature_evidence

## Company

- Ownership: independent
- Stage: series-c [source](https://fly.io/blog/we-raised-a-bunch-of-money/)
- Accelerators: Y Combinator Winter 2020 [source](https://www.ycombinator.com/companies/fly-io)
- Total raised: $107M (confirmed: Sum of confirmed rounds: $12M (Series A, Aug 2021) + $25M (Series B, closed June 2022) + $70M (EQT Ventures-led round, announced June 2023), all stated directly by the company/TechCrunch.) [source](https://fly.io/blog/we-raised-a-bunch-of-money/)
- Last round: series-c, $70M, 2023-06, led by EQT Ventures (confirmed) [source](https://fly.io/blog/we-raised-a-bunch-of-money/)
- Investors: Andreessen Horowitz, EQT Ventures, Intel Capital, Dell Technologies Capital, Initialized Capital, Sam Lambert (PlanetScale CEO, angel)
- Revenue: unknown

Fly.io (maker of 'Sprites') was founded 2017 by Kurt Mackey (previously founder of MongoHQ/Compose, sold to IBM in 2015) and went through Y Combinator Winter 2020. Confirmed rounds: $12M Series A (Aug 2021, led by Intel Capital), $25M Series B (closed June 2022, led by Andreessen Horowitz with Intel Capital, Dell Technologies Capital, Initialized Capital and Sam Lambert), and $70M (announced June 2023, led by EQT Ventures) — total $107M confirmed. No later financing round, acquisition, or revenue/ARR disclosure was found as of 2026-09-30; company remains independent and privately held.

## Caveats

- Pricing section says 'No plans and no tiers' while the FAQ on the same page (and Fly's 2026-09-09 article) describe optional plans; Hero $100 is confirmed current. Other tier prices/allowances come from the 2026-01-16 community post; the 2026-01-22 release note listed a different set (Recruit free, Adventurer $20, Legend $200, Mythic $2,000).
- Plan fee is NOT credit: it buys per-resource unit allowances (CPU-h, RAM GB-h, storage GB-month) that are not fungible (Fly staff post 2026-01-16: "Usage beyond included amounts is billed at standard usage-based rates"). Encoded as included_cpu_h / included_ram_gib_h / included_storage_gib_month on each plan with included_usd 0, so the engine (which only knows a fungible included_usd) never credits unused CPU hours against RAM overage; until the engine consumes the buckets, plans are never auto-picked over PAYG and the PAYG price is an upper bound for heavy users. Fly account credits cannot pay plan fees.
- Storage: disk_gib_month 0.02 is COLD storage on all bytes written, billed for as long as kept (including while awake). HOT storage $0.000683/GB-h ($0.50/GB-mo) additionally bills on the awake working set (mode key disk_gib_h_running). Checkpoint storage not priced separately; snapshot_gib_month 0.02 assumes checkpoints are billed as cold storage (unverified).
- Memory is billed on actual usage; the engine's ram_util drives the bill. Release note 2026-03-25: "Sprites now start with 2 GB of memory and can autoscale up to 16 GB based on demand"; the lifecycle page publishes no figure ("A Sprite doesn't run with one published RAM figure."). max_ram_gib 16 is that autoscale ceiling, not a reservable size (a Jan 2026 support reply had said 16 GB was 'not available yet').
- Fixed shape: 8 vCPU, 100 GB filesystem ceiling, one managed Ubuntu image (no custom image), no region selection, no public IPv4/SSH.
- Rates history: 2025-12-30 RAM $0.011/GB-h, CPU $0.07/CPU-h and storage $0.10/GB-mo; later CPU $0.07 and RAM $0.04375; from 2026-10-01 CPU $0.0385/CPU-h (the 2026-09 pricing-update notice said $0.03825) and RAM $0.021875/GB-h (checked on fly.io/pricing 2026-10-14). Plan allowances are unit buckets, so their dollar value roughly halved with the cut.
- PAYG running-concurrency cap unpublished (concurrency null). Limits return errors, never extra charges.
- Egress/bandwidth not metered today (egress_gib 0).
- No benchmark data in benchmarks.json (perf null); docs claim warm resume 100-500 ms, cold wake 1-2 s.
- Docker runs inside a Sprite, but a 2026-05-26 community report shows "docker exec will fail for any container whose PID 1 is non-root" (Postgres, Redis, node images) because the capability bounding set is restricted to 16 of 41 Linux capabilities; --cap-add SYS_PTRACE/IPC_LOCK also fail. No systemd: services run via the Sprites services API (https://community.fly.io/t/27956, https://docs.fly.io/sprites/concepts/services.md).

## How this provider charges


Sprites are persistent Firecracker microVMs for agents. Each Sprite always has **8 vCPUs** and a **100 GB** filesystem ceiling; memory is platform-managed (8 GB in practice, 16 GB advertised "not available yet"). Billing is **usage-based on what the VM actually consumes while awake**:
- CPU on cumulative CPU time (`cpu.stat`), $0.07/CPU-hour,
- memory on actual usage, $0.04375/GB-hour,
- storage on bytes written: **hot** $0.000683/GB-h while awake, **cold** $0.000027/GB-h for as long as data is kept.

The pricing section says "No plans and no tiers, and nothing charged per Sprite", but the FAQ on the same page and Fly's 2026-09-09 comparison article still describe **optional plans** (Hero $100/mo etc.). The Hero plan still exists (optional). What changes the bill is the lifecycle state, the RAM actually resident, and whether an optional plan bundle is bought.

## Regime table

| # | Regime | When it applies | How billed | Numbers | Source |
|---|---|---|---|---|---|
| 1 | Pay-as-you-go, running (active) | Command running, session producing output, open TCP connection to URL, service handling traffic, Tasks API hold | CPU on **actual CPU time** (30% of 4 vCPU for 1 h = 1.2 CPU-h); RAM on **actual resident memory**; hot storage on bytes written | $0.07/CPU-h; $0.04375/GB-h; hot $0.000683/GB-h (~$0.50/GB-mo at 730 h) | https://fly.io/pricing, https://fly.io/sprites |
| 2 | Warm (suspended) | ~30 s after last activity; VM suspended with memory frozen, resumes in 100-500 ms | **Not billed** for CPU/RAM/hot storage (FAQ: "warm (not billed)"). Cold storage continues | cold $0.000027/GB-h | https://fly.io/sprites, https://docs.fly.io/sprites/concepts/lifecycle/ |
| 3 | Cold (stopped) | Later, memory dropped; 1-2 s wake, processes restart | Cold storage only | $0.000027/GB-h (~$0.02/GB-mo) | same |
| 4 | Cold storage while awake | All written data, all the time | Pricing example bills cold on the full dataset **and** hot on the awake working set during a session (e.g. "Hot 5 GB × 4 h" + "Cold 10 GB × 4 h") | $0.000027/GB-h always + $0.000683/GB-h while awake | https://fly.io/sprites (examples) |
| 5 | Checkpoints | Automatic (after continuous work, on idle, on shutdown) + manual; copy-on-write, tiered history | No separate price. Presumably counted as stored bytes (cold) | not published separately | https://docs.fly.io/sprites/concepts/checkpoints |
| 6 | Optional plans (Adventurer → Mythic) | Org subscribes (seat-based plans, upgrade immediate, downgrade next period) | **Fee is not credit**: it buys an allowance of CPU-h, RAM GB-h and storage GB-month, plus higher concurrency/creation-rate limits and support. Overage at standard rates. Fly account credits cannot pay the plan fee | Adventurer $20 (450 CPU-h, 1,800 GB-h, 50 GB, 20 running/20 warm); Veteran $50 (800 / 3,200 / 100, 50/50); **Hero $100 (1,200 / 4,800 / 150, 100/100)**; Champion $200 (1,800 / 7,200 / 225, 200); Legend $500 (3,200 / 12,500 / 400, 500); Epic $1,000 (4,800 / 18,750 / 600, 1,000); Mythic $2,000 (7,200 / 28,000 / 900, 2,000); Guild custom | https://community.fly.io/t/more-sprites-plans/26857 (2026-01-16), https://fly.io/sprites FAQ, https://fly.io/learn/ai-sandbox-pricing/ |
| 7 | Concurrency / rate limits | Per org | Hitting a limit returns an error, never an extra charge. Cold Sprites unlimited | PAYG creates 10/min; Adventurer 60/min … Mythic 240/min; running/warm caps = plan table (PAYG cap not published) | https://fly.io/sprites FAQ |
| 8 | Trial credit | New user/org | One $30 grant per user, max one per org (a second org you create gets none) | $30 one-time | https://fly.io/sprites FAQ |
| 9 | Egress / bandwidth | Any | **Not metered** today | $0 | https://fly.io/sprites FAQ |
| 10 | Support | Plans | Hero/Champion/Legend Standard email; Epic/Mythic Premium; PAYG/Adventurer/Veteran community | bundled in plan | https://fly.io/sprites FAQ |
| 11 | Enterprise / huge fleets | "Need a truly wild number of Sprites?" | Talk to sales (Guild plan) | unpublished | https://fly.io/sprites |
| 12 | Historical: Dec 2025 rates | 2025-12-30 release note | CPU $0.07/vCPU-h, RAM **$0.011/GB-h**, storage $0.10/GB-mo. RAM was later raised ~4x to $0.04375 (date not found) and storage split into hot/cold (2026-01-22) | superseded | https://fly.io/sprites/release-notes |
| 13 | Historical: Jan 2026 plan set | 2026-01-22 release note | Recruit (free), Adventurer $20, Legend $200, Mythic $2,000. Conflicts with the 2026-01-16 community table (Legend $500) — the 7-tier table matches the current FAQ names | superseded / conflicting | https://fly.io/sprites/release-notes |

## Gotchas

1. **Memory is the big line item** (FAQ says so). $0.04375/GB-h is ~6x Fly Machines' extra-RAM rate; 8 GB resident for 1 h costs $0.35, more than 4 fully busy CPUs ($0.28). Keeping per-Sprite memory low saves more than any plan.
2. **CPU is truly usage-based**: idle-but-awake Sprites pay near-zero CPU, but RAM still bills while awake. Anything that keeps a Sprite awake (open TCP connection to its URL, a chatty session, stdout output, Tasks API hold) keeps RAM billing.
3. **Plan fee is not a credit.** It buys unit allowances (CPU-h / RAM GB-h / storage). A bigger plan is not automatically cheaper; the FAQ cites a customer near Mythic's 28,000 GB-h for whom $2,000 cost more than the overage it saved. Account credits cannot pay the plan fee.
4. **The pricing page contradicts itself** ("no plans and no tiers" vs a FAQ full of plans). Plans are optional; Hero is still quoted in Sep 2026.
5. Fixed shape: 8 vCPU, ~8 GB RAM cap in practice, 100 GB disk, no custom image, **no region choice**, no public IPv4, no native SSH. Open TCP connections drop on every warm/cold transition.
6. Storage is on bytes written (TRIM-aware), but cold storage bills on everything you keep, forever, until deleted — including while the Sprite is awake.
7. Billing granularity is described as "metered per hour of active use" / "billed hourly, based on actual usage"; the exact rounding is not published.

## Worked example

Workload: 4 vCPU / 8 GiB, 50 concurrent × 8 h/day × 22 days = **8,800 awake Sprite-hours**, 30% CPU util, 50 GiB snapshots retained, 100 GiB egress. (Sprite has 8 vCPU; only actual CPU time bills.)

Usage: CPU = 8,800 × 4 × 0.30 = **10,560 CPU-h** ($739.20). RAM assumed fully resident at 8 GB (upper bound) = **70,400 GB-h** ($3,080.00); a 50% (4 GB) resident case is also shown. Storage assumptions: 10 GB written per Sprite, hot while awake 10 × 8,800 × $0.000683 = $60.10; cold on 500 GB all month = $9.86; 50 GiB checkpoints in cold = $0.99 → **storage $70.95** (plan storage allowances not applied, since how they offset hot vs cold is unpublished). Egress $0. Sprites sleep outside hours (warm/cold: not billed).

| Regime | Fee | CPU overage | RAM overage | Storage | **Total (8 GB resident)** | Total (4 GB resident) |
|---|---|---|---|---|---|---|
| Pay-as-you-go | $0 | $739.20 | $3,080.00 | $70.95 | **$3,890.15** | $2,350.15 |
| Adventurer $20 (20 running cap) | invalid: 50 concurrent > 20 | | | | n/a | n/a |
| Veteran $50 (50 running) | $50 | $683.20 | $2,940.00 | $70.95 | **$3,744.15** | $2,204.15 |
| Hero $100 | $100 | $655.20 | $2,870.00 | $70.95 | **$3,696.15** | $2,156.15 |
| Champion $200 | $200 | $613.20 | $2,765.00 | $70.95 | **$3,649.15** | $2,109.15 |
| **Legend $500** (cheapest) | $500 | $515.20 | $2,533.13 | $70.95 | **$3,619.27** | **$2,079.27** |
| Epic $1,000 | $1,000 | $403.20 | $2,259.69 | $70.95 | **$3,733.84** | $2,193.84 |
| Mythic $2,000 | $2,000 | $235.20 | $1,855.00 | $70.95 | **$4,161.15** | $2,621.15 |
| (Historical Dec-2025 RAM rate $0.011, PAYG) | $0 | $739.20 | $774.40 | — | ~$1,514 + storage | — |

Notes: the idle tail is ~30 s before warm (negligible). The $30 trial credit reduces month 1 only. PAYG running-concurrency cap is unpublished (Hero caps at 100 running), so PAYG with 50 concurrent is assumed allowed.

Sources: https://fly.io/pricing · https://fly.io/sprites · https://docs.fly.io/sprites/concepts/lifecycle/ · https://docs.fly.io/sprites/concepts/checkpoints · https://fly.io/sprites/release-notes · https://community.fly.io/t/more-sprites-plans/26857 · https://community.fly.io/t/more-ram-in-sprites/26921 · https://fly.io/learn/ai-sandbox-pricing/