Top Fly.io Sprites alternatives for secure AI code execution and sandboxed environments

If you're building AI agents, code interpreters, or platforms that execute untrusted code, Fly.io Sprites (and Fly.io Sprites alternatives) might be on your radar. But depending on your needs, BYOC deployment, GPU support, OCI container images, or enterprise features, you may need to explore alternatives.

This guide examines the leading Fly.io Sprites alternatives, comparing isolation technologies, deployment options, pricing models, and production readiness.

We wrote a detailed explanation of container isolation and everything you need to know about it here. Use it as a primer before going deeper into Fly.io Sprites alternatives.

Fly.io Sprites launched in January 2026 as stateful sandbox environments for AI coding agents. Built on Firecracker microVMs, they offer:

• Persistent 100GB root filesystem using NVMe for fast local storage plus object storage for durability
• Checkpoint/restore that takes ~300ms and captures entire environment state
• Scale-to-zero after 30 seconds of inactivity
• HTTP access via unique URLs with automatic TLS
• Network policies for controlling egress

Sprites are designed for individual developers using Claude Code. They create in 1-12 seconds and automatically idle when inactive, billing only for actual CPU, memory, and storage usage.

Unlike standard Fly Machines, Sprites don't use Docker images. They use a custom storage stack where you start from a base Linux environment and install dependencies manually or via checkpoint/restore. This is a deliberate design choice, Fly.io argues that avoiding container image pulls enables faster creation times (1-2 seconds vs. potentially minutes for large images).

Note: Fly.io does offer GPUs (L40S, A100) for Fly Machines, but Sprites specifically are CPU-only. If you need GPU sandboxes, you'd use Fly Machines with Docker images, not Sprites.

Sprites solve a specific problem well: giving individual developers persistent sandboxes for Claude Code. But teams building production AI applications often need:

• Any OCI image support: Use existing containers without manual setup
• BYOC deployment: Run in your AWS/GCP/Azure accounts for compliance and data residency
• GPU support in sandboxes: Sprites are CPU-only; Fly GPUs require Fly Machines
• Multi-region deployment: Global distribution with predictable latency
• Enterprise features: Audit logs, SSO, RBAC, compliance tools
• Multi-tenant isolation: Platform-grade security for SaaS applications
• Complete infrastructure: Databases, APIs, and more beyond sandboxes

Northflank stands out by offering multiple isolation technologies and deployment flexibility. Since 2019, we've processed millions of workloads for companies like Writer, Sentry, and cto.new.

• Any OCI image: Bring any container from Docker Hub, GitHub Container Registry, or private registries, no manual dependency installation required
• Choice of isolation: Kata Containers (microVM), gVisor, Firecracker, or Cloud Hypervisor based on your security requirements
• True BYOC: Deploy in your AWS, GCP, Azure, or bare-metal infrastructure with full control
• GPU support in sandboxes: NVIDIA L4, A100, H100, and H200 available for isolated workloads
• Multi-region: 330+ availability zones globally
• Complete platform: Run databases, APIs, cron jobs, and GPU workloads alongside sandboxes
• Enterprise features: SSO, RBAC, audit logging, SOC 2 compliance tools

Bring any container: With Sprites, you start from a base Linux environment and install dependencies manually (or checkpoint a configured environment). This enables fast creation but means you can't directly deploy existing container images. Northflank accepts any OCI-compliant image without modification; deploy existing containers from any registry and integrate with CI/CD pipelines that produce Docker images.

Stronger isolation options: Sprites use Firecracker only. Northflank gives you Kata Containers with Cloud Hypervisor for true microVM isolation, gVisor for user-space kernel protection, or Firecracker for lightweight workloads.

Infrastructure flexibility: Sprites run exclusively on Fly.io infrastructure. Northflank deploys in your cloud accounts, keeping data in your VPC for compliance and cost optimization. Use existing cloud commitments and savings plans.

GPU support for sandboxes: Sprites are CPU-only. While Fly.io offers GPUs for Fly Machines, those use Docker images and different orchestration. Northflank provides GPU-enabled sandboxes (L4, A100, H100, H200) with the same microVM isolation and API as CPU workloads.

Production scale: Northflank processes millions of isolated workloads monthly, powering multi-tenant platforms for public companies and governments. Sprites launched in January 2026 and are designed for individual developer workflows rather than platform-scale multi-tenancy.

Northflank

• CPU: $0.01667/vCPU/hour
• RAM: $0.00833/GB/hour
• NVIDIA H100: $2.74/hour (all-inclusive)

Fly.io Sprites

• CPU: $0.07/CPU-hour
• RAM: $0.04375/GB-hour
• Hot storage: $0.000683/GB-hour
• Cold storage: $0.000027/GB-hour
• GPUs: Not available for Sprites (Fly Machines required)

Sprites (averaging 30% of 2 CPUs, 1.5GB RAM, 5GB storage):

• CPU (2.4 CPU-hrs): $0.17
• Memory (6 GB-hrs): $0.26
• Storage: $0.01
• Total: ~$0.44

Northflank (2 vCPU, 4GB RAM for 4 hours):

• Compute: $0.13
• Total: ~$0.13

For sustained workloads, Northflank's predictable per-second billing is more cost-effective than Sprites' usage-based model with separate CPU, memory, and storage charges.

Sprites are CPU-only. If you need GPU sandboxes on Fly.io, you'd use Fly Machines (which require Docker images and different tooling). Northflank provides GPU-enabled sandboxes with the same isolation and APIs as CPU workloads:

Northflank's GPU pricing includes CPU and RAM, approximately 62% cheaper than Modal for equivalent configurations.

E2B specializes in AI code execution with Firecracker microVMs and polished SDKs. Great for hackathons and demos but lacks production features.

Pros: ~150ms cold starts, excellent Python/JavaScript SDKs, AI framework integrations (LangChain, OpenAI, Anthropic)

Cons: 24-hour session limit, no self-hosting, expensive at scale, sandbox-only platform

Best for: AI agent developers who need reliable sandboxes with excellent SDK design and don't require sessions longer than 24 hours.

Modal provides a serverless platform optimized for machine learning and data workloads, with sandboxing as one capability within a broader compute fabric.

Pros: Massive autoscaling (20,000+ concurrent containers), Python-first DX, built-in GPU support, snapshot primitives

Cons: gVisor only (no microVM isolation), SDK-defined images only, no BYOC, Python orchestration required

Best for: Python ML teams who want serverless simplicity and don't need infrastructure flexibility.

Daytona pivoted to AI code execution in 2026, focusing on fast container starts with optional enhanced isolation.

Pros: Sub-90ms cold starts, Docker ecosystem compatibility

Cons: Docker containers by default (weaker isolation than microVMs), limited persistence, streaming stability issues reported

Best for: Quick prototypes and demos where speed matters more than isolation strength.

Vercel's beta sandbox offering provides Firecracker microVMs tightly integrated with their platform.

Pros: Great DX for Vercel users, Firecracker isolation, simple SDK

Cons: 45-minute session limit, Vercel ecosystem only, no BYOC, limited to Node.js and Python

Best for: Teams already on Vercel who need short-lived sandboxes for development workflows.

With Sprites, you start from scratch on every environment. Northflank accepts any OCI-compliant image from any registry, Docker Hub, GitHub Container Registry, your private registry, without modifications or SDK requirements.

Sprites use Firecracker only. Northflank gives you:

• Kata Containers: Full microVM isolation with Cloud Hypervisor
• gVisor: User-space kernel with syscall interception
• Firecracker: Lightweight microVMs for ephemeral workloads
• Cloud Hypervisor (CLH): High-performance VM isolation

• Your cloud: Deploy in your AWS/GCP/Azure accounts
• Compliance: Keep data in your VPC for regulatory requirements
• Hybrid: Mix Northflank-managed and self-hosted deployments
• Cost optimization: Use existing cloud commitments and spot instances

Northflank runs your complete stack:

• Secure code execution
• Backend APIs with load balancing
• Databases (PostgreSQL, MySQL, MongoDB, Redis)
• Scheduled jobs and cron workloads
• GPU inference and training
• CI/CD pipelines with GitOps

Since 2019, Northflank has solved the operational challenges others haven't:

• Multi-tenant isolation for SaaS platforms
• Resource quotas and autoscaling
• Audit logging and compliance tools
• Enterprise SSO and RBAC
• 330+ availability zones globally

Choose Sprites if: You're an individual developer using Claude Code who wants fast-creating persistent sandboxes with checkpoint/restore and don't need BYOC, GPUs, or OCI container support.

Choose E2B if: You need quick AI demos with polished SDKs and don't require sessions longer than 24 hours.

Choose Modal if: You're Python-first and comfortable with SDK-defined images for ML workloads.

Choose Northflank if: You need production-grade isolation, any OCI image support, BYOC deployment, GPU workloads, or a complete platform beyond just sandboxes.

Specialized sandboxing tools have their place, but modern AI applications need more than just isolated code execution.

Northflank leads because it's the only platform that combines:

• Enterprise-grade microVM isolation (Kata Containers using CLH)
• Any OCI container image support
• True BYOC deployment (AWS, GCP, Azure, bare metal)
• GPU support with all-inclusive pricing
• A complete platform for all your workloads
• Production scale
• Transparent, predictable pricing

With Northflank, secure AI execution is just one part of a comprehensive infrastructure solution that grows with your needs.

Try Northflank today or book a demo with a Northflank engineer.

Yes. While Sprites don't use standard container images, you can containerize your environment and deploy it directly on Northflank. Northflank accepts any OCI-compliant image, making migration straightforward once you've packaged your dependencies.

Northflank uses persistent volumes that maintain state across sessions. While the mechanism differs from Sprites' checkpoint/restore approach, the practical outcome (preserving environment state indefinitely) is the same. Sandboxes persist until you terminate them.

Firecracker (used by Sprites, E2B, Vercel) is a lightweight VMM designed for fast boot times. Kata Containers (available on Northflank) provides OCI-compatible containers running in lightweight VMs with Cloud Hypervisor, offering stronger isolation with broader compatibility. Both provide hardware-level isolation superior to container-only solutions.

Yes. Northflank supports NVIDIA L4, A100 (40GB and 80GB), H100, and H200 GPUs with all-inclusive pricing and the same microVM isolation as CPU workloads. Sprites are CPU-only; if you need GPUs on Fly.io, you'd use Fly Machines (which require Docker images and different tooling than Sprites).

Yes. Northflank's BYOC (Bring Your Own Cloud) deployment runs in your VPC with full infrastructure control. Same APIs, same experience, your cloud credits and commitments. Sprites run exclusively on Fly.io infrastructure.

For sustained workloads, Northflank's predictable per-second billing ($0.01667/vCPU/hour, $0.00833/GB/hour) is typically more cost-effective than Sprites' separate CPU ($0.07/CPU-hour), memory ($0.04375/GB-hour), and storage charges. Sprites' scale-to-zero is advantageous for intermittent usage; Northflank is better for sustained or predictable workloads.

Northflank offers true production-ready BYOC, letting you deploy in your AWS, GCP, Azure, or bare-metal infrastructure. E2B's self-hosting is experimental. Sprites, Modal, and Vercel are managed-only.

Yes. Northflank's microVM isolation provides the same security guarantees as Sprites for running AI coding agents. You can run Claude Code, Codex, or any AI agent in isolated environments with full network control and persistent storage.