LangFast

LangFast

Langfa.st
+
+

Related Products

  • Google AI Studio
    41 Ratings
    Visit Website
  • Checksum.ai
    2 Ratings
    Visit Website
  • Apify
    1,800 Ratings
    Visit Website
  • AI Video Cut
    1 Rating
    Visit Website
  • SmartDraw
    573 Ratings
    Visit Website
  • Adobe Firefly
    25,051 Ratings
    Visit Website
  • HubSpot AEO
    151 Ratings
    Visit Website
  • NodeMaven
    1,065 Ratings
    Visit Website
  • Evertune
    1 Rating
    Visit Website
  • ZipRecruiter
    14,382 Ratings
    Visit Website

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

Meet Ape, the first AI prompt engineer. Equipped with tracing, dataset curation, batch testing, and evals. Ape achieves an impressive 93% on the GSM8K benchmark, surpassing both DSPy (86%) and base LLMs (70%). Continuously optimize prompts using real-world data. Prevent performance regression with CI/CD integration. Human-in-the-loop with scoring and feedback. Ape works with the Weavel SDK to automatically log and add LLM generations to your dataset as you use your application. This enables seamless integration and continuous improvement specific to your use case. Ape auto-generates evaluation code and uses LLMs as impartial judges for complex tasks, streamlining your assessment process and ensuring accurate, nuanced performance metrics. Ape is reliable, as it works with your guidance and feedback. Feed in scores and tips to help Ape improve. Equipped with logging, testing, and evaluation for LLM applications.

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

Anyone seeking a solution to create, manage, and generate AI prompts

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 Not 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

Weavel
United States
weavel.ai/

Alternatives

Alternatives

Categories

Prompt Engineering Supported

Categories

Integrations

No info available.

Integrations

No info available.
Claim LangFast and update features and information
Claim LangFast and update features and information
Claim Weavel and update features and information
Claim Weavel and update features and information