# Mosaic Sandbox

Official pricing: https://sandbox.mosaicos.com/  
Category: agent-sandbox · Isolation: firecracker

## Pricing regimes (raw)

- **Active compute, $0.05 per billing unit per awake hour (hibernated = $0)** (sizes): 1 vCPU / 2048 MiB (bills as 1 unit) 1 vCPU/2 GiB $0.05/h; 2 vCPU / 4096 MiB (default, 1 unit, kept warm) 2 vCPU/4 GiB $0.05/h; 4 vCPU / 8192 MiB (2 units, cold boot) 4 vCPU/8 GiB $0.1/h; 8 vCPU / 16384 MiB (4 units, base template only, cold boot) 8 vCPU/16 GiB $0.2/h; 16 vCPU / 32768 MiB (8 units, base template only, cold boot) 16 vCPU/32 GiB $0.4/h

## Features

Yes: snapshots, memory snapshots, fork/clone, pause/resume, persistent disk, whole disk survives a stop, volumes, idle auto-stop, ≥24 h sessions, custom image (Docker or snapshot), start from your own snapshot, your own Docker/OCI image, full VM (own kernel), Docker inside, root, preinstalled agents, SSH, HTTPS preview URLs, custom domains, egress allowlist, open internet, SSO, Python, Node.js, credential injection, wake on request, live fork (no pause), memory fork, audit logs, scoped API keys, MCP server, usage per sandbox (API), automatic snapshots, snapshots on demand, agent harness API, gVisor or VM (no shared kernel), inbound access rules, firewall inside (nftables), secret proxy, secret proxy for any API, extra volumes, shared volumes, FUSE mounts, kernel features (eBPF, mounts, cgroups)

No: nested virtualization, browser, desktop GUI, computer-use API, code interpreter, browser + desktop control, anti-bot stealth, CAPTCHA solving, residential IPs, public IPv4, raw TCP inbound, static egress IP, self-hosting, BYOC, open source, SOC 2, HIPAA, GPU, arm64, Windows, macOS, GPU desktop, HTTP method/path egress rules, live resize, EU data residency, spend limits, hosted agent API (their own agent), fast boot (benchmarked)

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

## Company

- Ownership: independent
- Stage: unknown
- Accelerators: none found
- Total raised: unknown
- Revenue: unknown

Mosaic Sandbox (sandbox.mosaicos.com) is a Firecracker/KVM microVM execution API for coding agents run under the brand 'Mosaic OS'. No public information on founders, funding, accelerators, investors, revenue, or headcount could be found (search engines returned no relevant hits, Crunchbase/LinkedIn were inaccessible). Site currently requires a hosted-checkout to bill usage, and contact is a single named individual (nitin@mosaicos.com), consistent with a very early-stage / bootstrapped or unfunded project rather than an established company.

## Caveats

- Not mosaic.so (an unrelated AI video-editing company whose $40/$125 credit plans were scraped by mistake earlier). This card is Mosaic Sandbox at sandbox.mosaicos.com (PyPI mosaic-sandbox), the ComputeSDK 'mosaic' provider.
- Unit confirmed 2026-09-28 on sandbox.mosaicos.com/pricing and docs: 1 billing unit = 2 vCPU / 4 GB at $0.05/h ($0.00001389/s); 1 vCPU / 2 GB still bills as 1 unit; 4/8 = 2 units, 8/16 = 4, 16/32 = 8.
- 'Includes RAM and storage' and '$0 while hibernated': storage and snapshot costs set to 0. Archived sandboxes (persist:true, 7-day retention), named environments (reclaimed after ~30 days unused) and Mosaic Object Storage volumes have no published price; assumed free, unverified.
- Larger shapes (4/8 and up) are cold boots because only the default shape is kept warm.
- Egress is $0 (pricing: 'Network egress Outbound traffic from the sandbox $0 No per-GB charge'; llms.txt: 'egress is priced at $0: outbound traffic has no separate charge; only awake sandbox time is billed', checked 2026-10-14). No public IPv4 (HTTPS previews + SSH), so no IPv4 price.
- No published plans, free tier, minimums, or volume discounts; checkout required before use.
- Regions: US only (Silicon Valley, Northern Virginia).
- Awake time is metered from the host record; if unreachable, billing falls back to wall-clock lifetime ('estimated' accounting status).
- Pricing page: 'RBAC, SSO, and audit logs included' (sso=true); no SOC 2 / HIPAA claim found.
- Plan/concurrency: no plan tiers; up to 200 sandboxes alive at once per organization, hibernated ones included, across all keys ('Self-serve · Contact us to raise it', pricing page, checked 2026-10-14). API rate limit 1,000 req / 5 s per org. Fleet capacity can still refuse a create (429 capacity_unavailable).
- Pricing page now says 'One SKU for everyone, at three sizes' and lists only 1/2 GB, 2/4 GB (default) and 4/8 GB; the 8/16 and 16/32 shapes (base template only, 4 and 8 units) are still in the docs /v1/limits body and on the roadmap 'Shipped' list, so they stay in the card.
- Volumes (/mnt/data, Mosaic Object Storage) hold files up to 78 GiB; still no published storage price. Archived (persist:true) sandboxes 'accrue no CPU metering' and are reclaimed after 7 days unresumed.
- Roadmap: the 'published concurrency ceiling' item has shipped (200 per org, see plan). 'Later': GPU-backed sandboxes, an EU region and more regions. Per-organization tariffs exist in the metering model (usage segments capture the 'organization/resource-profile tariff'), so negotiated rates are possible, but no discount is published.
- Docker inside runs only on the `base` template; node-20, node-22 and python-3.11 list docker under unavailable_tools (llms.txt, checked 2026-10-14).

## How this provider charges


Not to be confused with **mosaic.so** (an AI video editor with $40/$125 credit plans). Mosaic Sandbox is a Firecracker
microVM sandbox (PyPI `mosaic-sandbox`, the ComputeSDK "mosaic" provider). It has a single metered regime: **$0.05 per hour
of awake ("active") compute, RAM and storage included, $0 while hibernated**. Larger shapes cost 2x/4x/8x units. The
host hibernates a sandbox after **3 quiet seconds**, so agent workloads that wait on LLMs pay for bursts only. A
running process, though, keeps the sandbox awake.

4 vCPU / 8 GiB = 2 units = **$0.10/h** awake (1 unit = 2 vCPU / 4 GB, confirmed on sandbox.mosaicos.com/pricing: "$0.00001389 / second, at 2 vCPU / 4 GB. The 4 vCPU guest bills as two of those").

## Regime table

| Regime | When it applies | How billed | Numbers | Source |
|---|---|---|---|---|
| Active compute, default shape | Sandbox awake, 2 vCPU / 4096 MiB (kept warm) | Per awake second (meter `sandbox_active_seconds`), RAM + storage included | $0.05/h | https://sandbox.mosaicos.com/, https://sandbox.mosaicos.com/docs/ |
| Larger shapes | 4/8192 (all templates); 8/16384, 16/32768 (`base` template only) | Metered at units occupied; cold boot (only default kept warm) | 2x = $0.10/h, 4x = $0.20/h, 8x = $0.40/h | https://sandbox.mosaicos.com/llms.txt |
| Small shape 1 vCPU / 2048 MiB | Any template | "The 1 vCPU guest still bills as one" unit | $0.05/h (same as default) | https://sandbox.mosaicos.com/pricing |
| Idle hibernation | Automatic after 3 quiet seconds (no running process); wakes on use; also explicit `pause` | Not metered | $0 | https://sandbox.mosaicos.com/docs/ |
| Archived (`persist: true`) | Sandbox reaches its TTL deadline | Resumable under same id within 7-day retention | unpublished (assumed $0) | docs |
| Named environments / snapshots | Built from image, Dockerfile or repo+setup | Reclaimed when unused past `environments.retention_seconds` (~30 d); max 100/org | unpublished (assumed $0) | llms.txt |
| Volumes (Mosaic Object Storage) | Up to 4 mounts, shared across hosts | unpublished | null | llms.txt |
| Fork / fan-out (1–32 children) | Children from parent memory image | Each awake child metered | $0.05/h per unit per child | llms.txt |
| Billing account | Before first use | Hosted checkout ("requires_checkout"); metered subscription | No base fee, plan, free tier or trial published | https://sandbox.mosaicos.com/docs/ |
| Egress | All traffic | Allowlist/eBPF policy; no price or quota published | null | docs |

Dated changes: none published.

## Gotchas

1. **"Quiet" means no running processes.** "A running process prevents hibernation." Dev servers, file watchers, `sleep` loops or a long agent process keep the sandbox awake and billed. The 3-second hibernation only helps request/response-style agent turns.
2. **Unit confirmed (verify 2026-09-28)**: the pricing page states $0.05/h is "at 2 vCPU / 4 GB"; 4 vCPU bills as two units and the 1 vCPU guest still bills as one, so downsizing below 2/4 saves nothing. If the host awake-time record is unreachable, billing falls back to wall-clock lifetime.
3. **Non-default shapes are cold boots.** Only 2/4 is kept warm, so 4/8 and above lose the fast-start advantage.
4. **"Includes storage"** covers the running sandbox. Archived sandboxes, named environments and volumes have no published storage price.
5. No published egress price, free tier or concurrency cap ("fleet capacity bound"). US regions only.
6. **Name collision**: the mosaic.so pricing page (video credits) is sometimes cited for this sandbox. It is unrelated.

## Worked example

Workload: 4 vCPU / 8 GiB (2 units), 50 concurrent × 8 h/day × 22 days = **8,800 sandbox-hours**, 30% CPU,
50 GiB snapshots, 100 GiB egress.

| Regime | Feasible? | Monthly total |
|---|---|---|
| Awake the whole session (processes keep it awake) | Yes | 8,800 × $0.10 = **$880.00** |
| Awake only 30% of the session (hibernates between bursts) | Yes, if no long-running processes | 2,640 h × $0.10 = **$264.00** |
| Default 2 vCPU / 4 GiB instead (half the RAM) | If the workload fits | 8,800 × $0.05 = $440.00 |
| Snapshots 50 GiB | Hibernated state: $0; archived/named environments: unpublished | $0 (assumed) |
| Egress 100 GiB | Price unpublished | excluded |