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Cloud · head to head

Azure Functions vs OpenTelemetry

Azure Functions logo

Azure Functions

Cloud

Event-driven serverless compute on Azure

From
Free
Rated
-
Full reviewWebsite
OpenTelemetry logo

OpenTelemetry

Cloud

Vendor-neutral standard for traces, metrics and logs

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Azure Functions consumption plan free grant is capped at 1 million executions and 400,000 GB-seconds of resource consumption per month per subscription, billed per GB-second beyond that; OpenTelemetry genuinely complex to adopt: collectors, pipelines, samplers and exporters are a system to run in their own right

Where they differ

Only the attributes on which Azure Functions and OpenTelemetry actually diverge.

Attributes where Azure Functions and OpenTelemetry differ
AttributeAzure FunctionsOpenTelemetry
Pricing modelusage-basedOpen source, no licence fee
PlatformsWebLinux, macOS, Windows, Kubernetes, Docker

Identical on both: starting price (Free), free tier (Yes), 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 Azure Functions

Nothing recorded that OpenTelemetry does not also cover.

Only in OpenTelemetry

  • Vendor-neutral SDKs
  • Collector
  • Three signals
  • Auto-instrumentation

What people use each for

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

Azure Functions

  • Event-driven computingnot OpenTelemetry
  • Serverless application backendnot OpenTelemetry
  • Scalable API endpointsnot OpenTelemetry

OpenTelemetry

  • Instrumenting once and keeping the option to change observability vendor laternot Azure Functions
  • Standardising telemetry across services written in different languagesnot Azure Functions
  • Routing and filtering telemetry centrally to control observability spendnot Azure Functions

Where each one falls short

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

Azure Functions

  • Consumption plan free grant is capped at 1 million executions and 400,000 GB-seconds of resource consumption per month per subscription, billed per GB-second beyond that
  • The newer Flex Consumption plan's free grant is smaller still, at 250,000 executions and 100,000 GB-seconds per month
  • Premium plan avoids per-execution charges but bills continuously for allocated core seconds and memory regardless of invocation volume
  • Memory is rounded up to the nearest 128 MB and execution time to the nearest 1 ms for billing, so small overages round upward

OpenTelemetry

  • Genuinely complex to adopt: collectors, pipelines, samplers and exporters are a system to run in their own right
  • Language SDKs mature at different rates, so a polyglot estate gets uneven support
  • It produces and moves telemetry but does not store or visualise it, so a backend is still required and still billed

Pricing, plan by plan

Azure Functions

Free
  • Consumption Plan$null/month
    • 1 million requests free monthly
    • 400,000 GB-seconds free monthly
    • Billed per second and executions
  • Flex Consumption Plan$null/month
    • 250,000 executions free monthly
    • 100,000 GB-seconds free monthly
    • Event-driven scaling
  • Premium Plan$null/month
    • No execution charges
    • At least one instance required
    • Includes automatic scaling and VNET access

OpenTelemetry

Free
  • OpenTelemetryFree
    • Full functionality
    • No usage limits
    • Community support

Which should you pick?

Choose Azure Functions if

  • You want to start without paying.
Azure Functions review

Choose OpenTelemetry if

  • You need vendor-neutral sdks.
  • You want to start without paying.
  • You work on Linux, macOS, Windows, Kubernetes, Docker.
  • You also want collector.
OpenTelemetry review

Questions people ask

Is Azure Functions or OpenTelemetry better?
Neither clearly leads. Azure Functions starts at Free and OpenTelemetry at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Azure Functions or OpenTelemetry?
Azure Functions starts at Free and OpenTelemetry at Free.
Does Azure Functions or OpenTelemetry run on more platforms?
Azure Functions runs on Web. OpenTelemetry runs on Linux, macOS, Windows, Kubernetes, Docker.
Can I use Azure Functions for free?
Both have a free tier, so you can try either at no cost before committing.
What is Azure Functions best used for?
Azure Functions is most often used for event-driven computing, serverless application backend, scalable api endpoints. Of those, event-driven computing and serverless application backend are not what OpenTelemetry is typically brought in for.
What can Azure Functions do that OpenTelemetry cannot?
OpenTelemetry covers Vendor-neutral SDKs, Collector, Three signals, Auto-instrumentation.

Answered from the vendors’ own pages

Azure Functions: Does Azure Functions have a free tier?

Yes, Azure Functions includes a monthly free grant of 1 million requests and 400,000 GB-seconds on the Consumption Plan, or 250,000 executions and 100,000 GB-seconds on Flex Consumption.

Source
OpenTelemetry: Is OpenTelemetry free?

Yes, open source under the CNCF. What you pay for is the backend you export to.

Azure Functions: What is Azure Functions' pricing model?

Azure Functions uses usage-based pricing. Consumption plans charge per second of resource consumption and per execution, measured in gigabyte-seconds and rounded to the nearest 128 MB.

Source
OpenTelemetry: Does OpenTelemetry replace Datadog or Grafana?

No. It replaces their proprietary agents and instrumentation libraries. You still need a backend to store and query the data.

Azure Functions: What is the minimum execution time for Azure Functions?

The minimum execution time is 100 milliseconds on Consumption plans. Premium plans charge based on core seconds and allocated memory.

Source
OpenTelemetry: Why adopt a vendor-neutral standard?

Because instrumentation is the expensive part. Once code emits OTel, changing observability vendor is a collector config change instead of re-instrumenting every service.

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