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AI · head to head

AI21 Labs vs Seldon

AI21 Labs logo

AI21 Labs

AI

Enterprise language AI solutions

From
Free
Free plan
Yes
Full reviewWebsite
Seldon logo

Seldon

Machine Learning

Kubernetes model serving whose current version is licensed under the Business Source Licence

From
Free
Free plan
Yes
Full reviewWebsite

The short version

  • Each has a real cost: AI21 Labs the free allowance is $10 of credit lasting 7 days rather than an ongoing free tier; Seldon seldon Core v2 is under the Business Source Licence rather than Apache 2.0, so production use requires a commercial agreement, and a team that evaluated it believing it was open source discovers the licence is the blocker exactly when the project is ready to ship.
  • They diverge on capability: AI21 Labs covers Jamba models, Seldon covers Kubernetes custom resources.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which AI21 Labs and Seldon actually diverge.

Attributes where AI21 Labs and Seldon differ
AttributeAI21 LabsSeldon
Pricing modelusage-basedfreemium
PlatformsApi, CloudLinux
CategoryAIMachine Learning
Founded20172014

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).

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 AI21 Labs

  • Jamba models
  • Long context
  • RAG engine
  • Writing tools
  • REST API
  • Amazon Bedrock
  • Cloud platforms
  • Api support

Only in Seldon

  • Kubernetes custom resources
  • Inference graphs
  • Traffic strategies
  • Open Inference Protocol
  • Alibi Explain
  • Alibi Detect
  • Kafka-backed pipelines in v2
  • Commercial control plane

What people use each for

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

AI21 Labs

  • Running long-context tasks on the Jamba model familynot Seldon
  • Building and optimising production AI agents with Maestronot Seldon
  • Routing between models to control cost and accuracynot Seldon
  • Long-horizon agentic tasks needing stateful workspacesnot Seldon

Seldon

  • Serving an ensemble or a multi-stage inference path as one versioned deployment rather than as a chain of separate servicesnot AI21 Labs
  • Running genuine production experiments where a share of live traffic goes to a candidate model and the results are comparednot AI21 Labs
  • Regulated environments needing explanations and drift monitoring attached to the served model rather than bolted on laternot AI21 Labs
  • Organisations with an established Kubernetes platform team who want serving expressed as manifests under existing deployment controlsnot AI21 Labs

Where each one falls short

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

AI21 Labs

  • The free allowance is $10 of credit lasting 7 days rather than an ongoing free tier
  • Jamba Large is $2 per million input tokens and $8 per million output, so output-heavy work costs four times as much as input
  • Volume discounts, private cloud hosting and higher rate limits require a custom plan
  • Standard rate limits are not published

Seldon

  • Seldon Core v2 is under the Business Source Licence rather than Apache 2.0, so production use requires a commercial agreement, and a team that evaluated it believing it was open source discovers the licence is the blocker exactly when the project is ready to ship.
  • Core v1 remains Apache 2.0 but is in maintenance, so taking the free route means running software that receives no new development while the architecture it belongs to moves on without it.
  • Version 2 is a different system rather than a newer release, with different custom resources, a scheduler component and a Kafka-based pipeline model, so migrating from v1 is a re-implementation of every deployment manifest rather than an upgrade.
  • Kafka is a dependency for v2 pipelines, so an organisation that does not already operate it takes on a distributed log with its own storage, retention, rebalancing and failure modes purely in order to serve models.
  • Everything assumes Kubernetes fluency and the failure modes are Kubernetes failure modes, custom resource version mismatches, an operator that will not reconcile, admission webhooks and resource limits terminating an inference pod mid-request, so it needs a platform engineer rather than a data scientist.

Pricing, plan by plan

AI21 Labs

Free
  • Free TrialFree
    • 10 USD credits
    • 7-day trial period
    • No credit card required
  • Pay As You Go$undefined/mo
    • Usage-based pricing model
    • Access to all Foundation model APIs and SDK
    • Unlimited seats
  • Custom Plan$undefined/mo
    • Volume discounts on token pricing
    • Premium API rate limits
    • Private cloud hosting option

Seldon

Free
  • Seldon CoreFree
    • Open source
    • Kubernetes deployment
    • Model serving
  • Seldon DeployFree
    • Enterprise features
    • GUI
    • Monitoring

Which should you pick?

Choose AI21 Labs if

  • You need jamba models.
  • You want to start without paying.
  • You work on Api, Cloud.
  • You also want long context.
AI21 Labs review

Choose Seldon if

  • You need kubernetes custom resources.
  • You want to start without paying.
  • You work on Linux.
  • You also want inference graphs.
Seldon review

Questions people ask

Is AI21 Labs or Seldon better?
Neither clearly leads. AI21 Labs starts at Free and Seldon at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, AI21 Labs or Seldon?
AI21 Labs starts at Free and Seldon at Free.
Does AI21 Labs or Seldon run on more platforms?
AI21 Labs runs on Api, Cloud. Seldon runs on Linux.
Can I use AI21 Labs for free?
Both have a free tier, so you can try either at no cost before committing.
What is AI21 Labs best used for?
AI21 Labs is most often used for running long-context tasks on the jamba model family, building and optimising production ai agents with maestro, routing between models to control cost and accuracy, long-horizon agentic tasks needing stateful workspaces. Of those, running long-context tasks on the jamba model family and building and optimising production ai agents with maestro are not what Seldon is typically brought in for.
What can AI21 Labs do that Seldon cannot?
AI21 Labs covers Jamba models, Long context, RAG engine, Writing tools. Seldon covers Kubernetes custom resources, Inference graphs, Traffic strategies, Open Inference Protocol.

Answered from the vendors’ own pages

AI21 Labs: How much do AI21's Jamba Mini and Jamba Large models cost?

Jamba Mini costs $0.2 per 1M input tokens and $0.4 per 1M output tokens. Jamba Large is priced at $2 per 1M input tokens and $8 per 1M output tokens. Both models use usage-based billing with no monthly minimums.

Source
Seldon: Is Seldon open source?

Partly, and this is the thing to check before you build on it. Core v1 is Apache 2.0 but in maintenance. Core v2 was moved to the Business Source Licence in 2024, which allows evaluation but not unlicensed production use. Verify the current licence of each component you intend to run, including MLServer and the Alibi libraries.

AI21 Labs: Does AI21 offer a free trial?

Yes, AI21 provides a free trial with 10 USD in credits for 7 days, no credit card required. The trial grants access to all Foundation models via API and SDK.

Source
Seldon: What is the difference between v1 and v2?

Architecture, not just version number. v2 introduces a scheduler, a different set of custom resources and Kafka-backed pipelines. Manifests, mental model and operations all change, so treat a move as a project.

AI21 Labs: How do AI21's custom plans and volume discounts work?

Custom plans with volume discounts are available for enterprises but require contacting sales. These plans can include premium API rate limits, private cloud hosting, priority support, dedicated account managers, and expert consultancy.

Source
Seldon: Do I need Kubernetes?

Yes. It is a Kubernetes-native system and there is no meaningful deployment without a cluster and someone competent to run it.

AI21 Labs: What does AI21 mean by 30% token efficiency savings?

AI21 claims their tokenization delivers approximately 30% more text per token compared to other providers, which can reduce effective costs by roughly 30%. This applies primarily to English-language text averaging 1 word or 6 characters per token.

Source
Seldon: What is MLServer?

Seldon's Python inference server implementing the Open Inference Protocol, usable inside Seldon deployments or on its own. Check its current licence alongside Core's, since the company has moved projects onto the Business Source Licence.

Seldon: Do I have to run Kafka?

For v2 pipelines, yes. If you only need single models served, that dependency is a large amount of infrastructure for the benefit, and a simpler serving layer may be the better answer.

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