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Yes—AWS Lambda can run an asynchronous app without a Lambda charge if its monthly eligible usage stays within the listed free tier: 1 million requests and 400,000 GB-seconds per month. That is not a promise of a zero bill for the whole app: an HTTP front end, storage, queues, logs, or usage beyond allowances may cost extra. Lambda is best for event-triggered work that finishes within its execution limits, not a server that must run continuously.
Is your async app a good fit for Lambda?
Lambda runs code in response to invocations rather than keeping a server process running around the clock. That suits bounded tasks such as processing an uploaded file, handling a notification, responding to an event, or performing a short background job. AWS lists services including S3, SNS, EventBridge, Step Functions, and CloudWatch Logs as sources of Lambda events.
A function invocation is not the same as a durable job queue or a complete application platform. If a task needs a queue, database, persistent storage, or static asset hosting, those components must be provided separately and their usage priced separately.
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- Execution time: A standard Lambda function can run for at most 900 seconds (15 minutes). A worker that must run longer needs a different design or service.
- Payload size: AWS documents a 1 MB limit for asynchronous invocation payloads. Synchronous requests and responses have a 6 MB limit each. These are service quotas, not performance guarantees.
- Memory and CPU: You can configure 128 MB to 10,240 MB of memory; AWS allocates CPU in proportion to memory. Memory allocation affects both available resources and duration-based cost.
- Deployment package: Direct API or console uploads allow 50 MB zipped and 250 MB unzipped, including layers and custom runtimes. Larger upload packages can use S3. Container image packages have a separate 10 GB maximum uncompressed size.
Also consider burst volume and concurrency: a workload that arrives in large bursts can have different operational and billing implications from a steady trickle. The published limits do not establish how a particular app will perform.
Expose an HTTP handler with the simplest suitable front door
If your app needs a basic public HTTP or HTTPS endpoint, a Lambda Function URL is the most direct option. AWS describes it this way: “Lambda function URLs provide a simple, direct HTTP endpoint for a Lambda function.” Function URLs support built-in CORS and basic monitoring, and AWS says the URL endpoint itself has no additional charge. Requests still invoke Lambda, so Lambda usage and any other services remain relevant to the bill.
When a Function URL is enough
- You need a straightforward endpoint that invokes one Lambda function.
- Built-in CORS and the available basic monitoring meet your needs.
- You do not require the API-management controls available through API Gateway.
When API Gateway is worth considering
Choose API Gateway when the app needs capabilities such as request throttling, stage management, API keys, API documentation, WebSocket APIs, private APIs, or WAF integration. It adds a separate service and pricing model, so include its current charges in your estimate rather than assuming the Lambda allowance covers it. AWS describes an API Gateway free tier, but eligibility and amounts should be verified on its live pricing page.
For either front door, compare setup simplicity, the controls and protocols you need, traffic handling, monitoring, and total cost—including Lambda and connected services. A free endpoint does not make the services behind it free.
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How Lambda’s free allowance and bill work
AWS prices standard Lambda Functions by request count and execution duration. The listed monthly Lambda free tier is 1 million requests and 400,000 GB-seconds. AWS states: “The free tier includes one million requests and 400,000 GB-seconds per month.” These are Lambda allowances, not a single allowance for every part of an app.
Requests and duration are counted separately. Memory allocation affects the compute resources available and the duration pricing; the actual cost depends on the function’s memory, run time, request volume, and applicable account terms. AWS also counts asynchronous events as requests. For events larger than 256 KB, its pricing page describes additional request counts in 64 KB chunks up to 1 MB.
Other services can add charges, as can Lambda usage above applicable allowances. AWS distinguishes account plans, ongoing monthly allowances, and short-term trials; on a paid plan, eligible usage beyond credits or after credits expire is charged at standard rates. Check the live AWS Lambda pricing page and AWS account billing and free-tier information for current terms before deploying. The figures here reflect AWS pages accessed on October 7, 2026; the pages do not state a publication date, and terms can change.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Estimate the whole app before deploying
Use your own workload assumptions rather than treating the free tier as a blanket hosting guarantee. Estimate the following for the AWS Region and account plan you intend to use:
- Invocation volume: Count expected HTTP requests and asynchronous events, including bursts and retries where relevant.
- Duration and memory: Estimate average and upper-end execution times at the configured memory. These determine GB-seconds and influence cost.
- Payloads: Check typical and maximum event sizes against the synchronous or asynchronous payload limit that applies.
- Supporting services: List any API Gateway, queues, storage, database, logging, monitoring, or other services the design needs, then check each service’s current pricing and allowance separately.
- Account terms: Confirm which plan applies and whether credits, trials, or usage allowances cover the account and intended usage.
Only after those inputs are known can you judge whether the app is likely to stay within the relevant allowances. AWS’s Lambda pricing page and API Gateway pricing page are the appropriate starting points for a current estimate.
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