---
title: What's what in VIABLE
description: The VIABLE Learning Platform, the Developer Platform, the Engine and the Harness - what each is for, and which website is which.
updated: 2026-11-05
---

> All VIABLE docs, for people and their agents: https://developers.viablelab.org/llms.txt

# What's what in VIABLE

**VIABLE** is a family of tools for AI that teaches the way a teacher wants, made by [VIABLE Lab](https://www.viablelab.org). It has four parts, and you need only the one that fits what you want to do.

| You want to | Use | It is |
| --- | --- | --- |
| **Teach a class today**, with nothing to set up | [VIABLE Learning Platform](https://www.viablelearning.org) | Hosted. Say what you're teaching, and share a link |
| **Run a study, build agents, or call an API** | [VIABLE Developer Platform](https://developers.viablelab.org) | Hosted. Every setting, with nothing to run |
| **Run it all on your own server** | [VIABLE Engine](/docs/engine/overview) | Open source, under MIT |
| **Make an AI you already have teach well**, or have a coding agent build something for a classroom | [VIABLE Harness](/docs/harness/overview) | Open source, under MIT. A Skill, a command, or a package |

## The names

- **VIABLE** on its own means the whole family, never one part. It comes from the lab's name: Versatile Innovations in Affect, Behavior, and Learning Engineering.
- **VIABLE Lab** is the people, at the University of Florida. It's where to [ask for more credit, or anything else](https://www.viablelab.org/contact).
- **VIABLE Learning Platform** (VLP) is where teachers and learners go.
- **VIABLE Developer Platform** (VDP) is where researchers and builders work. These docs live here, and cover all four parts.
- **The VIABLE API** is how programs reach the Developer Platform. It's part of it, not a fifth thing.
- **VIABLE Engine** is the open server, and its **console** is its pages in a browser.
- **VIABLE Harness** goes around an AI: what it knows, what it may do, and whether the result is any good. It has two sides: [the AI that teaches](/docs/harness/how-it-works), and [the AI that builds](/docs/harness/for-builders).
- **VETTING** is one check inside the Harness, where a second reader reviews a reply before a learner sees it.
- **CHECKPOINT** and **LOGEN AI** are classroom tools of their own, reached from the Learning Platform.

## How they stand on each other

Each stands on the one below it, one way only, so nothing is built twice:

```text
VIABLE Developer Platform      VIABLE Learning Platform
everything, every setting      Ask, and simple forms
            \                    /
             the hosted API and learner pages
                       |
                 VIABLE Engine            agents, courses, class lists, pages
                       |
                 VIABLE Harness           what teaching needs around any AI
```

- **The same pages:** what a teacher sees on the Learning Platform is the Engine's console. A learner's page is the same on all three.
- **The same courses:** the Learning Platform and the Developer Platform are one account and one set of courses, under your Google sign-in. A course made in one shows in the other.
- **A way out:** a course or agent on the Developer Platform downloads as a package that runs on the Engine, and the other way round. Learners and their work don't travel in one.

## Which website is which

`viablelearning.org` is for teaching and learning. `viablelab.org` is for the lab and for building.

| Address | What it is | For |
| --- | --- | --- |
| [www.viablelearning.org](https://www.viablelearning.org) | The Learning Platform's front door, and where learners type a class code | Teachers and learners |
| [teach.viablelearning.org](https://teach.viablelearning.org) | Where a teacher sets up a class | Teachers |
| page.viablelearning.org | What learners open from a teacher's link. Nothing to sign up for | Learners |
| [developers.viablelab.org](https://developers.viablelab.org) | The Developer Platform, and these docs | Researchers, builders, developers |
| api.viablelab.org | The API, and the Harness's hosted MCP address | Programs |
| [github.com/VIABLE-Learning-Lab/viable](https://github.com/VIABLE-Learning-Lab/viable) | The Engine and the Harness | Developers, and a school's IT |
| [www.viablelab.org](https://www.viablelab.org) | VIABLE Lab: people, research, contact | Anyone |
| [checkpoint.viablelearning.org](https://checkpoint.viablelearning.org), [logen.viablelab.org](https://logen.viablelab.org) | Classroom tools | Teachers and students |

::: cards
- [Teach on the VIABLE Learning Platform](/docs/teach/learning-platform): a class running today.
- [Key ideas](/docs/start/key-ideas): agents, activities, studies and evidence, on the Developer Platform.
- [Open source](/docs/start/open-source): the Harness and the Engine.
- [Building for learners](/docs/harness/for-builders): if your AI is building the tool.
:::