Cloud & Infrastructure · head to head
Lambda (AWS Serverless) vs Fly.io
Lambda (AWS Serverless)
Cloud & Infrastructure
Run code without thinking about servers
- From
- Free
- Rated
- -
The short version
- Each has a real cost: Lambda (AWS Serverless) billed on two axes at once, $0.20 per million requests plus $0.0000166667 per GB-second of duration, so memory settings change the bill as much as traffic does; 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: Lambda (AWS Serverless) covers Function-as-a-Service, Fly.io covers Global deployment.
Where they differ
Only the attributes on which Lambda (AWS Serverless) and Fly.io actually diverge.
| Attribute | Lambda (AWS Serverless) | Fly.io |
|---|---|---|
| Platforms | Web, Api | Web, Api, Docker |
| Founded | 2014 | 2020 |
Identical on both: starting price (Free), pricing model (usage-based), free tier (Yes), user rating (Not yet rated), category (Cloud & Infrastructure).
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 Lambda (AWS Serverless)
- Function-as-a-Service
- Event-driven execution
- Pay-per-use
- Multiple languages
- Concurrency limits
- Dead Letter Queues
- Environment variables
- API Gateway
Only in Fly.io
- Global deployment
- Docker support
- Postgres databases
- Redis support
- Health checks
- Backups
- Monitoring
- Docker
Both cover
- Auto-scaling
- Cloud deployment
- Web support
What people use each for
The jobs each tool is most often brought in to do.
Lambda (AWS Serverless)
- Event-driven functions without managing serversnot Fly.io
- API backends behind API Gatewaynot Fly.io
- Processing S3, DynamoDB, SQS and Kinesis eventsnot Fly.io
- Scheduled jobs without a always-on instancenot Fly.io
- Edge compute through Lambda@Edgenot Fly.io
Fly.io
- Deploying containerised applications close to users across regionsnot Lambda (AWS Serverless)
- Running full stack apps and databases on managed machinesnot Lambda (AWS Serverless)
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
Lambda (AWS Serverless)
- Billed on two axes at once, $0.20 per million requests plus $0.0000166667 per GB-second of duration, so memory settings change the bill as much as traffic does
- Provisioned concurrency, used to avoid cold starts, is charged separately at $0.0000041667 per GB-second whether or not the function runs
- Ephemeral storage beyond the included 512 MB is metered
- Lambda@Edge costs $0.60 per million requests, three times the standard request rate
- VPC use and cross-region data transfer carry EC2 charges on top
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
Lambda (AWS Serverless)
Free- Free TierFree
- 1M free requests/month
- 400,000 GB-seconds/month
- Always free
Fly.io
Free- FreeFree
- 3 shared-cpu-1x VMs
- 3GB persistence storage
- 160GB outbound data/month
- Pay-as-you-goFree
- Unlimited applications
- Dedicated machines
- Global deployment
Which should you pick?
Choose Lambda (AWS Serverless) if
- You need function-as-a-service.
- You want to start without paying.
- You work on Web, Api.
- You also want event-driven execution.
Choose Fly.io if
- You need global deployment.
- You want to start without paying.
- You work on Web, Api, Docker.
- You also want docker support.
Questions people ask
- Is Lambda (AWS Serverless) or Fly.io better?
- Neither clearly leads. Lambda (AWS Serverless) starts at Free and Fly.io at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Lambda (AWS Serverless) or Fly.io?
- Lambda (AWS Serverless) starts at Free and Fly.io at Free.
- Does Lambda (AWS Serverless) or Fly.io run on more platforms?
- Lambda (AWS Serverless) runs on Web, Api. Fly.io runs on Web, Api, Docker.
- Can I use Lambda (AWS Serverless) for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is Lambda (AWS Serverless) best used for?
- Lambda (AWS Serverless) is most often used for event-driven functions without managing servers, api backends behind api gateway, processing s3, dynamodb, sqs and kinesis events, scheduled jobs without a always-on instance. Of those, event-driven functions without managing servers and api backends behind api gateway are not what Fly.io is typically brought in for.
- What can Lambda (AWS Serverless) do that Fly.io cannot?
- Lambda (AWS Serverless) covers Function-as-a-Service, Event-driven execution, Pay-per-use, Multiple languages. Fly.io covers Global deployment, Docker support, Postgres databases, Redis support. Both handle Auto-scaling, Cloud deployment, Web support.