Lambda Cloud vs Modal

Lambda Cloud

H100 SXM at $3.99 and B200 at $6.69 an hour with per-minute billing. No scale to zero, autoscaling or endpoints; an idle VM bills until terminated.

Modal

Scale to zero by default, per-second billing and about one-second container boots. No REST API or OpenAPI spec for deploying or invoking Functions.

Lambda Cloud

1. Call GET /instance-types first and read regions_with_capacity_available before trying to launch
2. Space launch calls 12 seconds apart; a sixth in a minute returns 429 with global/rate-limited
3. Branch on the error code, not the message or suggestion, which Lambda says may change
4. List instances before retrying a failed launch, since there's no idempotency key and a retry can start a second machine
5. Terminate the instance in a finally block; billing runs by the minute until you do

Modal

1. Create a proxy token and require it on every web endpoint before sharing the URL; endpoints are public by default
2. Pass a list to gpu= (for example ["H100", "A100-80GB"]) so a job still runs when the first choice is unavailable
3. Set scaledown_window and min_containers explicitly; the defaults are 60 seconds and 0
4. Use .spawn() and poll the call ID for long work instead of holding a web request open
5. Keep web endpoint traffic under 200 requests a second or ask Modal to raise the limit