Create and play endless AI-generated text adventures with customizable stories, characters, and choices online or via the app.
Harfi
$29Starting price
0Popularity
About Harfi
Harfi is a browser-based game where players craft instructions that force an AI model to produce outputs matching exact specifications. Each trial presents a set of rules—such as word counts, forbidden terms, or required formats like JSON or CSV—and players write prompts that generate compliant responses without writing the answers themselves. The tool uses a parser to score attempts by counting words, bullets, and scanning for banned elements, ensuring objective and consistent evaluation. Trials are grouped into five sets of eight, with the first set available permanently at no cost. Players can attempt each trial multiple times, aiming to meet or beat par, earn medals, and track progress via a scorecard. The AI model used is Claude Haiku 4.5, selected for its reliability rather than maximum capability, to maintain challenge. The platform emphasizes precision in AI interaction, particularly for tasks requiring structured or controlled outputs.
Key features
- Strict rule-based trials with word, bullet, and format constraints
- Parser-based scoring for consistent evaluation
- Five sets of eight trials each
- Medals for performance milestones (par, birdie, ace, minimalist)
- Scorecard tracking progress and achievements
- JSON, CSV, YAML, and table output formats
- Forbidden word and letter detection
- Multi-model reliability checks in Control set
Use cases
- Training precise AI prompt engineering skills
- Practicing structured data output generation
- Testing AI reliability for controlled responses
Pros
- Objective scoring via parser, not subjective evaluation
- Permanent free access to first set of trials
- No coding required; instructions written in plain English
- Focuses on precise AI output control and structured data formats
- No ads or data selling
Cons
- No free tier beyond the initial set of trials
- Limited to specific AI models (Claude Haiku 4.5)
- Requires browser access; no standalone desktop app
- No offline functionality
Frequently asked questions about Harfi
What is Harfi?
Harfi is a browser-based game where players craft instructions to control an AI model's output to match exact specifications. Each trial provides a set of rules—such as word counts, forbidden terms, or required formats—and players write prompts to generate compliant responses without writing the answers themselves.
How is Harfi scored?
Harfi uses a parser written in code to score attempts objectively. It counts bullets, words, parses structured formats like JSON, and scans for banned elements, ensuring consistent and transparent scoring without subjective evaluations.
Do I need to know how to code to use Harfi?
No coding knowledge is required. Players write instructions in plain English to guide the AI. Some trials involve structured outputs like JSON or CSV, but players describe the desired format rather than writing the code themselves.
Which AI model does Harfi use?
Harfi primarily uses Claude Haiku 4.5 for most trials. A second model is used in the reliability set to test prompt consistency across different models, ensuring the tool focuses on precision rather than maximum capability.
How many attempts do I get per trial?
Players can attempt each trial as many times as needed. There is no limit, and par serves as a target rather than a restriction. Clearing a trial in fewer strokes than par earns additional medals.
What is included in the free version of Harfi?
The free version includes Set 1, which consists of eight trials, and does not require an account or payment. Players can access their scorecard and attempt these trials indefinitely without expiry.
