Stop agents from hallucinating APIs.

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Supercharge your agents with spec-driven development

Get the speed of agentic coding with the reliability of production software

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Tessl Framework

The spec-driven development framework that keeps your agents on rails.

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Tessl Spec Registry

Stop agents from hallucinating APIs.

Explore the registry

Make your agents production ready

Founder and CEO, Guy Podjarny

TESSL FRAMEWORK

Keep agents on the rails

Left unchecked, agents drift: coding the wrong thing, hallucinating APIs, and breaking what already works. Tessl keeps agents aligned.

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Lock intent before you build

Agents define a spec before they write code and keep detailed plans updated as they go, ensure they stay on track

Make changes without regressions

Tests are integrated with your specs, enabling comprehensive regression test suites that validate your changes

Create long-term memory

Specs live in your project alongside your code, along with prior plans, ensuring that important details aren’t lost in ephemeral chats

Works with your stack and more

Spec-Driven Development is the next frontier in AI coding, and Tessl's exciting vision is to offer a true end-to-end solution for professional builders

Olivier Pomel, CEO at DataDog

Love how Tessl is inventing a new Agent Experience for docs. The way Tessl adds usage specs as project dependencies makes so much more sense than ad-hoc seeking online docs, and they can be structured perfectly for agents to efficiently consume.

Mathias Biilmann, CEO at Netlify

Tessl is the perfect antidote to vibe coding. Evolving the current best practice of defining project requirement documents, managing agent memory and context engineering in a natural direction towards disciplined specification driven development.

Martin Wimpress, Sr Software Engineer at Chainguard

You shouldn't have to choose between AI's power and reliable security - instead, we should give AI a secure palette to build from. Tessl provides finalized, trusted components so that AI can construct applications with speed, while ensuring every part of the foundation is consistent and secure

Caleb Sima, Chair of CSA AI Security Alliance

There is a big gap between writing code that simply compiles and maintainable code that can be managed at scale. What Tessl solves is the repeatable workflows, strong guardrails, and consistency required to build reliable production systems.

Armon Dadgar, Co-Founder and CTO of HashiCorp

There’s a huge gap between demo-ware and production-ware. Spec-driven frameworks like Tessl help bridge that gap, turning prototypes into trusted systems.

Des Traynor, Co-Founder of Intercom

What excites me about Tessl is how it brings structure and clear specifications into AI development, making it much easier to deliver the kind of trustworthy, production-ready software companies need.

Tamar Yehoshua, IVP Venture Partner & Advisor

What I love about Tessl is that it gives me structure and discipline I didn't know I needed. The spec-driven approach means I can walk away from a project, come back later, and immediately understand where I left off without having to decode someone else's code - even when that someone is an AI.

Alan Pope, Director or Developer Relations at Anchore

Spec-Driven Development is the next frontier in AI coding, and Tessl's exciting vision is to offer a true end-to-end solution for professional builders

Olivier Pomel, CEO at DataDog

Love how Tessl is inventing a new Agent Experience for docs. The way Tessl adds usage specs as project dependencies makes so much more sense than ad-hoc seeking online docs, and they can be structured perfectly for agents to efficiently consume.

Mathias Biilmann, CEO at Netlify

Tessl is the perfect antidote to vibe coding. Evolving the current best practice of defining project requirement documents, managing agent memory and context engineering in a natural direction towards disciplined specification driven development.

Martin Wimpress, Sr Software Engineer at Chainguard

You shouldn't have to choose between AI's power and reliable security - instead, we should give AI a secure palette to build from. Tessl provides finalized, trusted components so that AI can construct applications with speed, while ensuring every part of the foundation is consistent and secure

Caleb Sima, Chair of CSA AI Security Alliance

There is a big gap between writing code that simply compiles and maintainable code that can be managed at scale. What Tessl solves is the repeatable workflows, strong guardrails, and consistency required to build reliable production systems.

Armon Dadgar, Co-Founder and CTO of HashiCorp

There’s a huge gap between demo-ware and production-ware. Spec-driven frameworks like Tessl help bridge that gap, turning prototypes into trusted systems.

Des Traynor, Co-Founder of Intercom

What excites me about Tessl is how it brings structure and clear specifications into AI development, making it much easier to deliver the kind of trustworthy, production-ready software companies need.

Tamar Yehoshua, IVP Venture Partner & Advisor

What I love about Tessl is that it gives me structure and discipline I didn't know I needed. The spec-driven approach means I can walk away from a project, come back later, and immediately understand where I left off without having to decode someone else's code - even when that someone is an AI.

Alan Pope, Director or Developer Relations at Anchore

Spec-Driven Development is the next frontier in AI coding, and Tessl's exciting vision is to offer a true end-to-end solution for professional builders

Olivier Pomel, CEO at DataDog

Love how Tessl is inventing a new Agent Experience for docs. The way Tessl adds usage specs as project dependencies makes so much more sense than ad-hoc seeking online docs, and they can be structured perfectly for agents to efficiently consume.

Mathias Biilmann, CEO at Netlify

Tessl is the perfect antidote to vibe coding. Evolving the current best practice of defining project requirement documents, managing agent memory and context engineering in a natural direction towards disciplined specification driven development.

Martin Wimpress, Sr Software Engineer at Chainguard

You shouldn't have to choose between AI's power and reliable security - instead, we should give AI a secure palette to build from. Tessl provides finalized, trusted components so that AI can construct applications with speed, while ensuring every part of the foundation is consistent and secure

Caleb Sima, Chair of CSA AI Security Alliance

There is a big gap between writing code that simply compiles and maintainable code that can be managed at scale. What Tessl solves is the repeatable workflows, strong guardrails, and consistency required to build reliable production systems.

Armon Dadgar, Co-Founder and CTO of HashiCorp

There’s a huge gap between demo-ware and production-ware. Spec-driven frameworks like Tessl help bridge that gap, turning prototypes into trusted systems.

Des Traynor, Co-Founder of Intercom

What excites me about Tessl is how it brings structure and clear specifications into AI development, making it much easier to deliver the kind of trustworthy, production-ready software companies need.

Tamar Yehoshua, IVP Venture Partner & Advisor

What I love about Tessl is that it gives me structure and discipline I didn't know I needed. The spec-driven approach means I can walk away from a project, come back later, and immediately understand where I left off without having to decode someone else's code - even when that someone is an AI.

Alan Pope, Director or Developer Relations at Anchore

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Specs
SPEC REGISTRY

10,000+ specs for OSS libraries

Give agents the context to use open source correctly the first time and avoid endless fix cycles.

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Give your agents better context

Explore Spec Registry
Search specs like packages

Search specs like packages

Discover open source specs instantly across web, CLI, and MCP. Dependencies map directly to usage specs, using the package names you know.

Specs that update with your code

Specs that update with your code

Specs match and update across your project automatically, preventing version conflicts, staying current with fixes, and reducing maintenance overhead.

Keep your agents on the rails with Tessl

The Tessl Framework and Registry are now available in beta.

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