Softwr

Cloud · head to head

Caddy vs Fly.io

Caddy logo

Caddy

Cloud

Web server with automatic HTTPS by default

From
Free
Rated
-
Full reviewWebsite
Fly.io logo

Fly.io

Cloud

Deploy web applications globally

From
$29/month
Rated
-
Full reviewWebsite

The short version

  • Only Caddy has a free tier, so it costs nothing to try first.
  • Each has a real cost: Caddy smaller ecosystem than Nginx, so third-party guides and modules are fewer; Fly.io egress is priced by destination region, from $0.02 per GB in North America and Europe to $0.12 per GB for Africa and India, so the same traffic costs six times more depending on where users are
  • They diverge on capability: Caddy covers Automatic HTTPS, Fly.io covers Global deployment.

Where they differ

Only the attributes on which Caddy and Fly.io actually diverge.

Attributes where Caddy and Fly.io differ
AttributeCaddyFly.io
Starting priceFree$29/month
Pricing modelOpen source, no licence feeusage-based
Free tierYesNo
PlatformsLinux, macOS, Windows, DockerWeb, Api, Docker
FoundedUnknown2020

Identical on both: user rating (Not yet rated), category (Cloud).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Caddy

  • Automatic HTTPS
  • Caddyfile
  • Reverse proxy
  • Single binary

Only in Fly.io

  • Global deployment
  • Docker support
  • Postgres databases
  • Redis support
  • Auto-scaling
  • Health checks
  • Backups
  • Monitoring

What people use each for

The jobs each tool is most often brought in to do.

Caddy

  • Sites and services where expired certificates have caused outages beforenot Fly.io
  • Small deployments where Nginx configuration is more effort than the problem warrantsnot Fly.io
  • Reverse proxying internal services with TLS without a certificate workflownot Fly.io

Fly.io

  • Deploying containerised applications close to users across regionsnot Caddy
  • Running full stack apps and databases on managed machinesnot Caddy

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Caddy

  • Smaller ecosystem than Nginx, so third-party guides and modules are fewer
  • Adding plugins means rebuilding the binary rather than loading a module
  • Under very high throughput Nginx generally still benchmarks ahead
  • Automatic certificate issuance needs outbound internet access, which complicates air-gapped deployments

Fly.io

  • Egress is priced by destination region, from $0.02 per GB in North America and Europe to $0.12 per GB for Africa and India, so the same traffic costs six times more depending on where users are
  • Stopped machines still bill at $0.15 per GB of root filesystem a month, so a paused service is not a free one
  • Volumes are billed on provisioned capacity rather than usage, at $0.15 per GB a month
  • Reservation discounts of 40% require paying a year up front, from $36 to $1,440
  • Fly Kubernetes is a separate $75 a month per cluster
  • Dedicated IPv4 addresses are $2 a month each

Pricing, plan by plan

Caddy

Free
  • CaddyFree
    • Full functionality
    • Commercial use permitted
    • Community support

Fly.io

$29/month
  • Pay-as-You-Go$null/mo
    • Micro VMs and persistent storage charged by usage
    • FlyCTL CLI
    • Unlimited users and organizations
  • Serious Support$29/month
    • Access to dedicated engineering team
    • All Pay-as-You-Go features
  • Machine Reservation Blocks$null/mo
    • 40% discount on machine usage
    • Requires upfront payment for savings
  • Compliance Package$99/month
    • HIPAA compliance
    • BAAs
    • SOC2 documentation

Which should you pick?

Choose Caddy if

  • You need automatic https.
  • You want to start without paying.
  • You work on Linux, macOS, Windows, Docker.
  • You also want caddyfile.
Caddy review

Choose Fly.io if

  • You need global deployment.
  • You work on Web, Api, Docker.
  • You also want docker support.
Fly.io review

Questions people ask

Is Caddy or Fly.io better?
Neither clearly leads. Caddy starts at Free and Fly.io at $29/month, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Caddy or Fly.io?
Caddy has a free tier; the other does not. Paid plans start at Free for Caddy and $29/month for Fly.io.
Does Caddy or Fly.io run on more platforms?
Caddy runs on Linux, macOS, Windows, Docker. Fly.io runs on Web, Api, Docker.
Can I use Caddy for free?
Yes. Caddy has a free tier, so you can try it without paying. Fly.io starts at $29/month.
What is Caddy best used for?
Caddy is most often used for sites and services where expired certificates have caused outages before, small deployments where nginx configuration is more effort than the problem warrants, reverse proxying internal services with tls without a certificate workflow. Of those, sites and services where expired certificates have caused outages before and small deployments where nginx configuration is more effort than the problem warrants are not what Fly.io is typically brought in for.
What can Caddy do that Fly.io cannot?
Caddy covers Automatic HTTPS, Caddyfile, Reverse proxy, Single binary. Fly.io covers Global deployment, Docker support, Postgres databases, Redis support.

Answered from the vendors’ own pages

Caddy: Is Caddy free?

Yes, open source under the Apache 2.0 licence, free for commercial use.

Fly.io: Is there a free tier for Fly.io?

Fly.io does not advertise a free tier. The base plan is pay-as-you-go with usage-based pricing for Micro VMs and persistent storage. All users get FlyCTL CLI, unlimited organizations, private networking, SSO, ACLs, and scoped tokens.

Source
Caddy: What does automatic HTTPS mean?

Caddy obtains certificates from Let’s Encrypt or ZeroSSL on first request and renews them before expiry, with no cron job or configuration.

Fly.io: How much does Fly.io Serious Support cost?

Serious Support costs 29 USD per month and provides access to a dedicated engineering team while maintaining all pay-as-you-go features for Micro VMs and storage.

Source
Caddy: Caddy or Nginx?

Caddy is dramatically simpler to configure and removes certificate management. Nginx has the larger ecosystem and better peak throughput.

Fly.io: What does Fly.io Compliance Package include?

The Compliance Package is 99 USD per month and includes HIPAA compliance, BAAs, and SOC2 documentation for organizations requiring compliance certifications.

Source
Fly.io: Does Fly.io offer discounts for upfront commitment?

Yes, Fly.io offers Machine Reservation Blocks with 40% discount on machine usage. This requires upfront payment but applies savings on infrastructure costs.

Source
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