# 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): $0.03825/vCPU-h, $0.021875/GiB-h

## Features

Yes: snapshots, pause/resume, persistent disk, 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

No: memory snapshots, fork/clone, volumes, your own Docker/OCI image, nested virtualization, 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, 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

## 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. RAM cap ~8 GB in practice (16 GB advertised, 'not available yet' per Jan 2026 support reply). max_ram_gib 8.
- Fixed shape: 8 vCPU, 100 GB filesystem ceiling, one managed Ubuntu image (no custom image), no region selection, no public IPv4/SSH.
- FUTURE TARIFF (not yet applied; today 2026-09-28): effective 2026-10-01 CPU $0.03825/CPU-h and memory $0.021875/GB-h (fly.io/pricing-update; vendor example 2 CPU + 4 GB for 720 h: $226.80 -> $118.08). Storage rates unchanged. Card keeps current $0.07 / $0.04375 until then; the dollar value of plan allowances will roughly halve too.
- Rates history: 2025-12-30 RAM $0.011/GB-h and storage $0.10/GB-mo; current RAM $0.04375 (~4x higher; change date not found).
- 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.

## 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/