The best open source alternative to Stream is Parlant. If that doesn't suit you, we've compiled a ranked list of other open source Stream alternatives to help you find a suitable replacement. Other interesting open source alternatives to Stream are: Ethora and Tiledesk.
Stream alternatives are mainly Chatbot Platforms but may also be AI Agent Platforms or AI Chat Interfaces. Browse these if you want a narrower list of alternatives or looking for a specific functionality of Stream.
A conversational AI server that manages agent behavior through context-aware guidelines, keeping responses consistent, auditable, and aligned at scale.

Parlant is a self-hostable conversational AI server designed for teams building customer-facing agents that need to stay on-brand, on-policy, and predictable in production. It sits between your frontend and your LLM provider, managing every interaction through a structured control layer rather than relying on monolithic system prompts or rigid intent graphs.
The core idea is context engineering: instead of stuffing all your rules into one prompt and hoping the model follows them, Parlant dynamically assembles only the rules, data, and tools relevant to each turn. The result is that the 200th behavioral rule is as safe to add as the first, with no degradation in adherence.
Key capabilities:
This is a meaningful departure from tools like Rasa or flow-based builders. Changing agent behavior is a content change (add or edit a guideline), not a structural one (rewire a graph). That makes it practical for product teams to feed ongoing feedback directly into the agent without requiring engineering intervention for every adjustment.
Parlant is LLM-agnostic and works with OpenAI, Anthropic, Azure, and others. It's built for enterprise AI teams where tone, edge cases, and policy constraints aren't afterthoughts.
Looking for open source alternatives to other popular services? Check out other posts in the alternatives series and openalternative.co, a directory of open source software with filters for tags and alternatives for easy browsing and discovery.
Build branded chat apps with AI agents, group messaging, document exchange, and digital wallets using React and React Native components.

Ethora is a messaging SDK for developers and product teams who need to ship chat features fast, without building everything from scratch. It targets web, iOS, and Android through React and React Native components, and it covers both traditional team chat and AI-powered assistant functionality in one package.
The core use case is embedding a fully functional chat experience into an existing product. Drop in the React component, configure it to match your brand, and you have 1-on-1 messaging, group chats, file and document exchange, voice messages, reactions, and push notifications. The UI is fully customizable, so it can match your product's visual style rather than looking like a third-party widget.
Beyond basic messaging, Ethora includes:
The AI agent setup is handled through an admin panel. You configure a prompt, upload documents, or crawl your website, and the agent answers with context drawn from that material. Real-world deployments include a HIPAA-compliant healthcare chatbot indexing thousands of medical conference pages, and a workers' compensation platform connecting injured workers with caseworkers.
Ethora's front-end code (React Native mobile app, React web app, NPM component, WordPress plugin, and JS widget) is open source. The backend is closed source by default, but self-hosted and perpetual license options are available for teams that need full control or deep server-side customization.
Pricing starts at a free tier covering 1,000 monthly active users, with paid plans adding SLA guarantees, custom domains, and dedicated hosting. It's positioned as an alternative to building chat interfaces in-house, or to tools like Chatwoot or Typebot when you need both messaging and AI agents in a single SDK.
AI-enhanced live chat platform for seamless customer engagement, featuring chatbots, multichannel support, and advanced analytics.

Tiledesk revolutionizes customer support by combining the power of AI with human expertise. This innovative platform offers a comprehensive suite of tools designed to enhance customer engagement and streamline support operations.
Key benefits of Tiledesk include:
Tiledesk empowers businesses of all sizes to deliver exceptional customer experiences, increase satisfaction rates, and boost overall efficiency in their support operations.