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Machine Learning · head to head

Langwatch vs OpenSearch

Langwatch logo

Langwatch

Machine Learning

LLM engineering platform for testing and evaluating AI agents in production

From
Free
Rated
-
Full reviewWebsite
OpenSearch logo

OpenSearch

Databases

Open-source search and analytics suite forked from Elasticsearch

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Langwatch free plan limited to 50k events per month, restricting larger deployments; OpenSearch diverged from Elasticsearch since 7.10, so clients, plugins and features no longer map one to one
  • They diverge on capability: Langwatch covers Agent simulation testing, OpenSearch covers Full-text search.
  • Prices and features above were last checked on 29 August 2026.

Where they differ

Only the attributes on which Langwatch and OpenSearch actually diverge.

Attributes where Langwatch and OpenSearch differ
AttributeLangwatchOpenSearch
Pricing modelTiered subscription with usage-based overage chargesOpen source, no licence fee; managed services billed separately
PlatformsWeb, Docker, KubernetesLinux, Docker, Kubernetes, Self-hosted
CategoryMachine LearningDatabases

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 Langwatch

  • Agent simulation testing
  • LLM evaluation
  • OpenTelemetry tracing
  • Langy AI Engineer
  • Governance controls
  • Multiple deployment options
  • Framework support

Only in OpenSearch

  • Full-text search
  • OpenSearch Dashboards
  • Log analytics
  • Vector search

What people use each for

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

Langwatch

  • Continuous testing of AI agents before production deploymentnot OpenSearch
  • Automated test creation from product requirementsnot OpenSearch
  • LLM response quality evaluation and scoringnot OpenSearch
  • Production agent monitoring and cost trackingnot OpenSearch
  • Governance and access control for AI systemsnot OpenSearch

OpenSearch

  • Log and observability storage where an Apache-2.0 licence is a requirementnot Langwatch
  • Replacing Elasticsearch after the licence change without changing architecturenot Langwatch
  • Search plus analytics on one cluster rather than two systemsnot Langwatch

Where each one falls short

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

Langwatch

  • Free plan limited to 50k events per month, restricting larger deployments
  • Pricing in EUR may complicate budgeting for US-based teams
  • Usage-based overage model can create unpredictable costs
  • Self-hosted option requires DevOps expertise

OpenSearch

  • Diverged from Elasticsearch since 7.10, so clients, plugins and features no longer map one to one
  • Operationally heavy in the way Elasticsearch is: cluster sizing, shard strategy and JVM tuning are ongoing work
  • Smaller ecosystem of third-party tooling than Elasticsearch, which most integrations still target first
  • Overkill for plain application search, where a dedicated search engine is far simpler

Pricing, plan by plan

Langwatch

Free
  • DeveloperFree
    • 50k events per month
    • 14-day data access
    • 2 users
  • Growth$29/month
    • 200k events per month included
    • 5 EUR per 100k additional events
    • 30-day data retention
  • Enterprise$undefined/custom
    • Custom event limits
    • Hybrid, self-hosted or on-premises deployment
    • Custom SSO and RBAC

OpenSearch

Free
  • OpenSearchFree
    • Full functionality
    • Self-hosted
    • No usage limits

Which should you pick?

Choose Langwatch if

  • You need agent simulation testing.
  • You want to start without paying.
  • You work on Web, Docker, Kubernetes.
  • You also want llm evaluation.
Langwatch review

Choose OpenSearch if

  • You need full-text search.
  • You want to start without paying.
  • You work on Linux, Docker, Kubernetes, Self-hosted.
  • You also want opensearch dashboards.
OpenSearch review

Questions people ask

Is Langwatch or OpenSearch better?
Neither clearly leads. Langwatch starts at Free and OpenSearch at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Langwatch or OpenSearch?
Langwatch starts at Free and OpenSearch at Free.
Does Langwatch or OpenSearch run on more platforms?
Langwatch runs on Web, Docker, Kubernetes. OpenSearch runs on Linux, Docker, Kubernetes, Self-hosted.
Can I use Langwatch for free?
Both have a free tier, so you can try either at no cost before committing.
What is Langwatch best used for?
Langwatch is most often used for continuous testing of ai agents before production deployment, automated test creation from product requirements, llm response quality evaluation and scoring, production agent monitoring and cost tracking. Of those, continuous testing of ai agents before production deployment and automated test creation from product requirements are not what OpenSearch is typically brought in for.
What can Langwatch do that OpenSearch cannot?
Langwatch covers Agent simulation testing, LLM evaluation, OpenTelemetry tracing, Langy AI Engineer. OpenSearch covers Full-text search, OpenSearch Dashboards, Log analytics, Vector search.

Answered from the vendors’ own pages

Langwatch: Is there a permanent free tier?

Yes, Langwatch's Developer plan is free forever with 50k events per month, 14-day data access, 2 users, and no credit card required. It is specifically designed for individual developers prototyping AI applications.

Source
OpenSearch: Is OpenSearch free?

Yes, Apache 2.0 licensed under the Linux Foundation. Amazon OpenSearch Service is a paid managed option.

Langwatch: What is Langy and how does it save time?

Langy is an AI-powered tool that automates test creation. It converts product requirements into test scenarios, runs simulations, scores results, and generates pull requests with fixes in a median of 14 minutes.

Source
OpenSearch: Why does OpenSearch exist?

Elastic moved Elasticsearch off the Apache 2.0 licence in 2021. AWS forked the last Apache-licensed version, and the project now sits under the Linux Foundation.

Langwatch: What frameworks does Langwatch support?

Langwatch works with LangGraph, LangChain, CrewAI, OpenAI Agents, AWS Bedrock, Azure OpenAI, Vertex AI, and other major LLM frameworks and platforms.

Source
OpenSearch: Is OpenSearch compatible with Elasticsearch?

It was at the 7.10 fork point. Both have developed independently since, so compatibility weakens with every release and should be verified for the features you use.

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