Langfa.st vs. Auth.js
Langfa.st
Langfa.st is a fast and minimal playground for testing and refining AI prompts. It supports over 50 large language models, including OpenAI, Anthropic, Mistral, Cohere, Google, and others — all available instantly without setup. You can insert variables, use Jinja2 templating, and compare outputs across models. There’s no need to sign up or bring your own API keys — it works out of the box. Langfa.st was built to eliminate the friction of existing tools: complicated UIs, required credentials, or overpriced subscriptions. It gives AI teams and prompt engineers a clean, disposable space to experiment, debug, and iterate — all in one tab. Free to use. You only pay if you need more volume or power features.
Auth.js
Formerly known as NextAuth. It's is an open-source authentication library originally built for NextJS. Auth.js is free to use and comes with over 80 integrations for various third-party identity providers such as Google, Facebook, Auth0, Apple etc. You can use it with your own database if you choose to. It works with MySQL, Postgres, MSSQL and MongoDB. Auth.js is compatible with Next.js, SvelteKit and SolidStart as of March 2024.
Reviews
Reviews
| Item | Votes | Upvote |
|---|---|---|
| Works without login or API key | 1 | |
| Supports 50+ models out of the box | 1 | |
| Built-in support for variables and Jinja2 templating | 1 | |
| Instant response, no setup required | 1 | |
| Clean and distraction-free UI | 1 |
| Item | Votes | Upvote |
|---|---|---|
| No custom API key support (yet) | 1 | |
| Not ideal for running complex multi-turn chats | 1 |
| Item | Votes | Upvote |
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| No pros yet, would you like to add one? | ||
| Item | Votes | Upvote |
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| No cons yet, would you like to add one? | ||
Frequently Asked Questions
Langfa.st is specifically designed for testing and refining AI prompts, supporting over 50 large language models without the need for login or API keys. It offers a clean UI and built-in support for variables and Jinja2 templating, making it ideal for prompt engineers. In contrast, Auth.js is an authentication library focused on integrating various identity providers and does not cater to AI prompt testing. Therefore, for AI prompt testing, Langfa.st is the better choice.
No, Auth.js is not designed for AI prompt testing. It is an authentication library that integrates with various identity providers and is primarily used for managing user authentication in applications. Langfa.st, on the other hand, is specifically built for testing AI prompts and supports multiple language models, making it the appropriate tool for that purpose.
Langfa.st is designed to be user-friendly for developers working with AI prompts, offering a distraction-free UI and instant access to multiple models without setup. Auth.js, while also user-friendly for developers needing authentication solutions, requires integration with identity providers and database management, which may add complexity. Therefore, for ease of use in AI prompt testing, Langfa.st is more user-friendly.
Langfa.st is a fast and minimal playground for testing and refining AI prompts. It supports over 50 large language models, including OpenAI, Anthropic, Mistral, Cohere, Google, and others — all available instantly without setup. Users can insert variables, use Jinja2 templating, and compare outputs across models without needing to sign up or provide API keys.
Pros of Langfa.st include: it works without login or API key, supports over 50 models out of the box, has built-in support for variables and Jinja2 templating, provides instant responses with no setup required, and features a clean and distraction-free user interface.
Cons of Langfa.st include the lack of custom API key support at this time and it may not be ideal for running complex multi-turn chats.
Langfa.st is particularly beneficial for AI teams and prompt engineers who need a clean, disposable space to experiment, debug, and iterate on AI prompts without the friction of complicated UIs or required credentials.
Yes, Langfa.st is free to use. Users only pay if they need more volume or access to power features.
Auth.js, formerly known as NextAuth, is an open-source authentication library originally built for NextJS. It is free to use and offers over 80 integrations for various third-party identity providers such as Google, Facebook, Auth0, and Apple. Auth.js can also be used with your own database, supporting MySQL, Postgres, MSSQL, and MongoDB.
As of March 2024, Auth.js is compatible with Next.js, SvelteKit, and SolidStart.
Yes, you can use Auth.js with your own database. It supports MySQL, Postgres, MSSQL, and MongoDB.
Auth.js offers a variety of features including over 80 integrations with third-party identity providers like Google, Facebook, Auth0, and Apple. It is also compatible with multiple platforms such as Next.js, SvelteKit, and SolidStart, and supports various databases including MySQL, Postgres, MSSQL, and MongoDB.
