LangFast

LangFast

Langfa.st
+
+

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About

LangFast is a lightweight prompt testing platform designed for product teams, prompt engineers, and developers working with LLMs. It offers instant access to a customizable prompt playground—no signup required. Users can build, test, and share prompt templates using Jinja2 syntax with real-time raw outputs directly from the LLM, without any API abstractions. LangFast eliminates the friction of manual testing by letting teams validate prompts, iterate faster, and collaborate more effectively. Built by a team with experience scaling AI SaaS to 15M+ users, LangFast gives you full control over the prompt development process—while keeping costs predictable through a simple pay-as-you-go model.

About

Model Playground AI is a web‑based platform that lets you explore, compare, and prototype with over 150 (100+) leading AI models side by side in a single, unified interface. It provides two main modes, Explore for free‑form prompt testing and Workflows for guided, repeatable tasks, where you can adjust parameters (temperature, max tokens, etc.), submit prompts across multiple models simultaneously, and instantly see comparative outputs. Presets and saving options enable you to store your configurations and chat histories for easy reproducibility, while API endpoints and credit‑based subscriptions ensure seamless integration into your own applications without hidden markup fees. Its lightweight, no‑code design supports text, image, video, and code generation tasks in one dashboard, making it easy to benchmark model quality, optimize prompts, and accelerate AI‑driven projects.

Platforms Supported

Windows Not Supported
Mac Not Supported
Linux Not Supported
Cloud Supported
On-Premises Not Supported
iPhone Not Supported
iPad Not Supported
Android Not Supported
Chromebook Not Supported

Platforms Supported

Windows Not Supported
Mac Not Supported
Linux Not Supported
Cloud Supported
On-Premises Not Supported
iPhone Not Supported
iPad Not Supported
Android Not Supported
Chromebook Not Supported

Audience

Product teams, software engineers, prompt engineers, AI developers, ML researchers, startup founders, and technical writers working on AI-powered features or language model integrations.

Audience

Developers, data scientists and AI enthusiasts seeking a tool to compare, test and deploy multiple AI models

Support

Phone Support Not Supported
24/7 Live Support Not Supported
Online Not Supported

Support

Phone Support Not Supported
24/7 Live Support Supported
Online Supported

API

Offers API Not Supported

API

Offers API Supported

Screenshots and Videos

No images available

Screenshots and Videos

Pricing

$60 one time
Free Version Not Supported
Free Trial Supported

Pricing

Free
Free Version Supported
Free Trial Not Supported

Reviews/Ratings

Overall 0.0 / 5
ease 0.0 / 5
features 0.0 / 5
design 0.0 / 5
support 0.0 / 5

This software hasn't been reviewed yet. Be the first to provide a review:

Review this Software

Reviews/Ratings

Overall 0.0 / 5
ease 0.0 / 5
features 0.0 / 5
design 0.0 / 5
support 0.0 / 5

This software hasn't been reviewed yet. Be the first to provide a review:

Review this Software

Training

Documentation Not Supported
Webinars Not Supported
Live Online Not Supported
In Person Not Supported

Training

Documentation Supported
Webinars Not Supported
Live Online Supported
In Person Not Supported

Company Information

Langfa.st
Founded: 2025
United States
langfa.st/new

Company Information

Model Playground
United States
modelplayground.ai/

Alternatives

Alternatives

WhichModel

WhichModel

WhichModel.io
Kaptha AI

Kaptha AI

Actovision IT Solutions Pvt Ltd

Categories

Prompt Engineering Supported

Categories

AI Tools Supported

Integrations

Bria.ai Not Supported
FLUX.1 Not Supported
FLUX.2 Not Supported
GPT-Image-1 Not Supported
Gen-4 Not Supported
Grok Not Supported
HiDream.ai Not Supported
Ideogram AI Not Supported
Imagen 4 Not Supported
Stable Diffusion Not Supported

Integrations

Bria.ai Supported
FLUX.1 Supported
FLUX.2 Supported
GPT-Image-1 Supported
Gen-4 Supported
Grok Supported
HiDream.ai Supported
Ideogram AI Supported
Imagen 4 Supported
Stable Diffusion Supported
Claim LangFast and update features and information
Claim LangFast and update features and information
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