JFBench: Japanese instruction Following Benchmark

JFBench is a benchmark suite for evaluating Japanese LLM instruction-following performance. It provides scripts for generation, evaluation, summary, and visualization.

Setup

Dependencies are managed with uv.

uv sync

Some constraints use an LLM as a judge for evaluation. By default, gpt-oss-120b is used via OpenRouter. Set the OpenRouter API key in OPENROUTER_API_KEY.

export OPENROUTER_API_KEY="your_openrouter_api_key"

Scripts and Arguments

The scripts below live under src/jfbench.

Benchmark Run: src/jfbench/benchmark/eval.py

Example (evaluate a model on OpenRouter):

uv run python src/jfbench/benchmark/eval.py \
  --benchmark "ifbench" \
  --output-dir data/benchmark_results \
  --n-constraints "1,2,4,8" \
  --constraint-set "test" \
  --n-benchmark-data 200 \
  --model-specs-json  '[{"provider": "openrouter", "model": "qwen/qwen3-30b-a3b-thinking-2507", "model_short": "Qwen3 30B A3B Thinking 2507"}]'

Example (evaluate a local vLLM server): options are passed via extra_body. See src/jfbench/llm.py for details.

uv run python src/jfbench/benchmark/eval.py \
  --benchmark "ifbench" \
  --output-dir data/benchmark_results \
  --n-constraints "1,2,4,8" \
  --constraint-set "test" \
  --n-benchmark-data 200 \
  --model-specs-json  '[{"provider": "vllm", "model": "/path/to/model_to_evaluate", "model_short": "Model to evaluate", "extra_body": {"base_url": "http://localhost:8001/v1"}}]'\
  --judge-model-spec-json '{"provider": "vllm", "model": "/path/to/judge_model", "model_short": "Local vLLM Judge", "extra_body": {"base_url": "http://localhost:8000/v1"}}'

• --benchmark: Benchmark name. Currently only ifbench is supported. Default ifbench.
• --ifbench-dataset-path: Path to an external IFBench JSONL file. Default None, which uses the bundled dataset under data/.
• --output-dir: Directory for result JSONL files. Default data/benchmark_results.
• --with-generate/--no-with-generate: Enable or disable generation. Default enabled.
• --with-eval/--no-with-eval: Enable or disable evaluation. Default enabled.
• --override: Re-run even if matching entries already exist. Default disabled.
• --n-constraints: Number of constraints. Comma-separated values supported. Default 1.
• --constraint-set: Constraint set (training/test). Default test.
• --n-benchmark-data: Number of entries to use. If omitted, use all entries when n_constraints is 1. Required when n_constraints is 2 or higher.
• --seed: Random seed. Default 42.
• --model-specs-json (required): JSON string that lists the evaluated models.
• --judge-model-spec-json: JSON string for the judge model. By default, OpenRouter gpt-oss-120b is used with reasoning effort medium.
• --n-concurrent-generations: Concurrent generation requests. Use -1 to send all at once. Default -1.

Benchmark Summary: src/jfbench/benchmark/analyze.py

Example:

uv run python src/jfbench/benchmark/analyze.py \
  --results-path data/benchmark_results

• --results-path: JSONL file or directory to analyze. Default data/benchmark_results.jsonl.
• --constraint: Filter to records that include the named constraint.
• --show-generated: Show generated responses after the summary table.

Visualization: src/jfbench/visualization/visualize.py

Example:

uv run python src/jfbench/visualization/visualize.py \
  --input-dir data/benchmark_results \
  --output-dir visualization_output \
  --n-constraints 1 \
  --prompt-source ifbench

• --input-dir: Directory with result JSONL files. Default data/benchmark_results.
• --output-dir: Output directory for charts. Default visualization_output.
• --drop-incomplete: Drop rows without completed evaluations. Default disabled.
• --n-constraints (required): Constraint counts to include. Can be repeated or comma-separated.
• --prompt-source: Prompt sources to include. Only ifbench is supported. Can be repeated or comma-separated.
• --models: Filter to specific model names. Can be repeated.
• --constraint-set: Constraint set filters (training/test). Can be repeated or comma-separated. By default both are included.
• --model-label-map: JSON string mapping model labels.