Fly.io vs Clerk
Run your app close to users, globally
vs. User management and authentication as a service
Pricing tiers
Fly.io
Pay-as-you-go
No monthly fee. Machines billed per second. Free allocations: ~3 small shared machines + 3 GB volumes.
$0 base (usage-based)
Shared CPU 1x — 256 MB
Entry VM. 1 shared vCPU, 256 MB RAM. ~$2.02/month continuously on.
$2/mo
Performance 1x — 2 GB
Dedicated 1 vCPU, 2 GB RAM.
$32/mo
Reservation — Shared (1 yr)
$36/year for $5/mo credit (40% savings).
$36/mo
Shared CPU 8x — 16 GB
8 shared vCPU, 16 GB RAM.
$89/mo
Performance 16x — 128 GB
Dedicated 16 vCPU, 128 GB RAM.
$1014/mo
Enterprise
Custom. Dedicated capacity, SLA.
Custom
Clerk
Free
50k MAU included. No SSO/SAML. Perfect for side projects and early prototypes.
Free
Pro
$25/mo (or $20/mo annual). 50k MAU, $0.02 each after. 1 enterprise SSO connection per app. Webhooks, JWT templates, custom session duration.
$25/mo
Business
$300/mo (or $250/mo annual). Advanced organizations, enhanced support, additional enterprise features.
$300/mo
Enterprise
Custom. Volume MAU discounts, SLA, workspace-wide SAML SSO, dedicated support.
Custom
Free-tier quotas head-to-head
Comparing pay-as-you-go on Fly.io vs hobby on Clerk.
| Metric | Fly.io | Clerk |
|---|---|---|
| mao | — | 100 orgs/month |
| mau | — | 50000 users/month |
| sso connections | — | 0 connections |
Features
Fly.io · 14 features
- Auto Stop/Start — Machines auto-stop when idle, start on request (like scale-to-zero).
- Certs — Let's Encrypt + wildcard certs managed.
- Fly GPU — A100/L40S/A10 on-demand GPU machines.
- Fly Kubernetes (FKS) — Managed Kubernetes on Fly machines.
- Fly Machines — Firecracker microVMs. Start in <1s. Run any Docker image.
- Fly Postgres — Managed Postgres via Supabase partnership (2024). Also legacy self-run Postgres …
- fly-replay headers — Route request to another region at app level.
- Fly Volumes — Persistent SSD attached to a Machine. Encrypted at rest.
- Global Anycast — Single IP routes to the closest region automatically.
- LiteFS — Distributed SQLite with primary/replica across regions.
- Private Networks — 6PN WireGuard mesh. Connect machines across regions privately.
- Secrets — Encrypted env vars propagated to all regions.
- Tigris (partner) — S3-compatible storage for Fly apps. By partner.
- Upstash Redis (partner) — Managed Redis via Upstash.
Clerk · 15 features
- Account Portal — Hosted sign-in/user profile pages at accounts.yourapp.com — zero UI code, fully …
- Bot Protection — Cloudflare Turnstile CAPTCHA integrated into sign-up.
- Clerk Billing — Built-in Stripe-powered billing: subscriptions, plans, proration — ties directly…
- Enterprise SSO (SAML/OIDC) — SAML and OIDC for enterprise customers. Per-domain connection. Pro+ (1 included)…
- Impersonation — Act as a user from dashboard to debug. Logged.
- JWT Templates — Custom JWT issuance for third-party backends (Supabase, Hasura, Firebase, Convex…
- Machine Tokens (M2M) — API keys and machine tokens for service-to-service auth in addition to user sess…
- Multi-Factor Auth — TOTP (authenticator apps), SMS OTP, backup codes. Forced or optional per user.
- Organizations (B2B) — Multi-tenant orgs with roles, permissions, invitations, domain allowlist, and pe…
- Passkeys (WebAuthn) — Passwordless passkey sign-in with per-device biometrics.
- Prebuilt Components — Drop-in React components: <SignIn/>, <SignUp/>, <UserButton/>, <OrganizationSwit…
- Sessions — Server-side session tokens. Sliding expiration by default; configurable absolute…
- User Management — Full user CRUD, metadata (public/private/unsafe), email/phone verification, ban/…
- Waitlist Mode — Collect sign-ups before opening the app. Approve waitlist entries to activate ac…
- Webhooks — Events: user.created/updated/deleted, session.created, organization.* — delivere…
Developer interfaces
| Kind | Fly.io | Clerk |
|---|---|---|
| CLI | flyctl CLI | — |
| SDK | — | @clerk/astro, @clerk/backend / @clerk/clerk-sdk-node, @clerk/chrome-extension, @clerk/clerk-expo, @clerk/clerk-js (vanilla), @clerk/clerk-react, @clerk/clerk-react-native, @clerk/nextjs, @clerk/nuxt, @clerk/remix, clerk-sdk-go, clerk-sdk-python, clerk-sdk-ruby, @clerk/tanstack-start, @clerk/vue |
| REST | Machines API | Backend REST API, Frontend API |
| GRAPHQL | Fly GraphQL API | — |
| MCP | — | Clerk MCP |
| OTHER | Fly Postgres (wire) | Webhooks (Svix) |
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