Make agents work in real codebases
Give your agents versioned context and evals that improve agent API usage by up to 3.3X
Run in your project to find dependencies
Stop agents from misusing OSS APIs
See how versioned context and evals improve correct API usage by up to 3.3× across 300+ open-source libraries.
Read moreWorks With Any Agent
MCP compatible with all agents
Agents guess, mix versions, waste time and tokens.
Tessl makes context installable, ensuring agents use your open-source and private libraries correctly.
10,000+ Tessl tiles for OSS libraries
Give agents the context to use open source correctly the first time and avoid endless fix cycles.
Get startedBuild Smart with Open-Source
Find a package
Search Tessl tiles like packages
Discover OSS context instantly across web, CLI, and MCP. Dependencies map directly to Tessl tiles, using the package names you know
Context that updates with your code
Tessl tiles match and update across your project automatically, preventing version conflicts, staying current with fixes, and reducing maintenance overhead
Run in your project to find dependencies or explore Tessl Registry
Teach agents to build the right way in your environment
Share your directory layout rules, naming and styling conventions so every contribution is clean, consistent, and merge-ready.
From our community
Join us on DiscordSpec-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
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
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
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
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
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
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
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
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
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
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
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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