Langfa.St

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Langfa.st is a Coding & Development tool that provides an online LLM playground for rapid prompt testing and evaluation. Users can compare responses across multiple models side-by-side and iterate on prompts with their own API keys.

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At a glance

Pricing

Paid

Free tier

API

Yes

Skill level

Technical

About

What is Langfa.st?

Langfa.st offers an online LLM playground designed for rapid testing and evaluation of prompts. Users can run prompt tests across various models, compare responses side-by-side, debug results, and iterate on prompts efficiently, all within a single platform. It supports OpenAI/GPT models and allows users to bring their own API keys for low-latency responses. The platform includes features like prompt management, variables & templates, cost estimation, and collaboration tools, making it a comprehensive solution for prompt engineering. Langfa.st aims to streamline the prompt development process, offering a robust alternative to other LLM playgrounds.

Best used for

Ideal for developers and data scientists who need to rapidly test and evaluate prompts, compare responses from different LLMs, and debug their prompt designs. Especially valuable for iterating on prompts efficiently and collaborating on prompt engineering projects with integrated sharing features.

Common actions

test LLM prompts

compare AI models

debug prompt responses

manage prompt versions

evaluate prompt performance

Capabilities

Key features

LLM playground
Side-by-side model comparison
Bring your own API keys
Prompt management
Jinja2 templates
Cost estimation
Share links

Target Audience

developerdata scientiststartup founder

Integrations

Not yet documented

Pricing & Plans

Paid

Free

FAQs

What models can I use with Langfa.st?

Currently, Langfa.st supports OpenAI/GPT models. The platform is designed to be extensible, and users can request access to models from other providers. Future plans include support for Claude AI and Gemini AI models.

Do I need to provide my own API keys?

Yes, you need to provide your own API keys to run models on Langfa.st. These keys are securely transmitted and stored encrypted server-side, used only for provider calls, and not exposed back to your browser.

Can I compare multiple models side-by-side?

Yes, Langfa.st allows you to open multiple chat tabs to see how different models respond to the same prompt simultaneously. This feature is central to its rapid testing and evaluation capabilities.

What is the pricing model for Langfa.st?

Langfa.st offers a one-time payment model for lifetime access, with no subscriptions or hidden fees. There is also a 1-Year Pass option available. Prices do not include API costs or optional extra cloud storage.

Can I save and share my chat sessions?

Yes, Langfa.st provides a 'Share' button to manage sharing permissions. You can create public URLs for your chat sessions or grant access to specific email addresses for collaboration.

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Open Source & Models Code Assistants DevOps & Infrastructure No-Code / Low-Code Testing & QA Backend & APIs

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