Tinker Fine Tuning

Tinker API - Cloud LLM Fine-Tuning

Expert guidance for fine-tuning large language models using Tinker's managed cloud training API. Tinker handles GPU allocation, model hosting, and distributed training — you write the training logic, Tinker runs it on cloud infrastructure.

When to Use This Skill

Use Tinker when you need to:

• Fine-tune models up to 235B parameters without managing GPU infrastructure
• Run LoRA training on Qwen, Llama, DeepSeek, or GPT-OSS models
• Train vision-language models (Qwen3-VL)
• Implement custom RL loops (GRPO, PPO, importance sampling) on cloud GPUs
• Iterate quickly with a training API that handles hardware provisioning

Do NOT use Tinker when:

• You need full fine-tuning (not LoRA) — Tinker only supports LoRA
• You need to train custom architectures — Tinker supports specific model families
• You want to use your own GPUs — use Axolotl, Unsloth, or LLaMA-Factory instead
• You need offline/air-gapped training

Tinker vs Alternatives:

Quick Reference

Installation

pip install tinker tinker-cookbook
# TINKER_API_KEY must be set — connect Tinker in the OpenScience dashboard to sync your API key.
# Verify: [ -n "$TINKER_API_KEY" ] && echo "set" || echo "not set"

Workflow 1: Supervised Fine-Tuning (Cookbook)

Use this for standard SFT with JSONL or HuggingFace datasets.

Checklist

• Prepare data in JSONL chat format ({"messages": [...]})
• Choose base model (see model table below)
• Set hyperparameters (LR, batch size, epochs)
• Run training via Cookbook
• Monitor metrics (train_mean_nll, test/nll)
• Save and deploy weights

Implementation

import json
import chz
import asyncio
from tinker_cookbook.supervised import train
from tinker_cookbook.supervised.types import ChatDatasetBuilderCommonConfig
from tinker_cookbook.supervised.data import FromConversationFileBuilder
from tinker_cookbook.renderers import TrainOnWhat
from tinker_cookbook.model_info import get_recommended_renderer_name
from tinker_cookbook.hyperparam_utils import get_lr
from tinker_cookbook.tokenizer_utils import get_tokenizer

model_name = "Qwen/Qwen3-30B-A3B"
renderer_name = get_recommended_renderer_name(model_name)
num_epochs = 3
data_file = "training_data.jsonl"

common_config = ChatDatasetBuilderCommonConfig(
    model_name_for_tokenizer=model_name,
    renderer_name=renderer_name,
    max_length=2048,
    batch_size=128,
    train_on_what=TrainOnWhat.ALL_ASSISTANT_MESSAGES,
)

dataset_builder = FromConversationFileBuilder(
    common_config=common_config,
    file_path=data_file,
)

blueprint = chz.Blueprint(train.Config).apply({
    "log_path": "/tmp/sft-run",
    "model_name": model_name,
    "dataset_builder": dataset_builder,
    "learning_rate": get_lr(model_name),
    "lr_schedule": "linear",
    "num_epochs": num_epochs,
    "lora_rank": 32,
})

config = blueprint.make()
asyncio.run(train.main(config))

# --- Exact usage reporting (auto-captured by CLI) ---
tokenizer = get_tokenizer(model_name)
total_tokens = 0
with open(data_file) as f:
    for line in f:
        row = json.loads(line)
        text = " ".join(m.get("content", "") for m in row.get("messages", []))
        total_tokens += len(tokenizer.encode(text))
total_tokens *= num_epochs
print(f'\n[OPENSCIENCE_USAGE] {json.dumps({"service": "tinker", "event_type": "training", "model": model_name, "tokens_used": total_tokens})}')

Data Format

JSONL with chat messages (one per line):

{"messages": [{"role": "user", "content": "Translate to French: hello"}, {"role": "assistant", "content": "bonjour"}]}

TrainOnWhat Options

Workflow 2: Reinforcement Learning (GRPO-style)

Use this for training with reward functions — math reasoning, format compliance, verifiable tasks.

Checklist

• Define reward function(s) that return float scores
• Choose group size (16 recommended)
• Set up sampling → reward → training loop
• Monitor correct, format, reward/total, KL divergence
• Keep KL below 0.01 for stable training

Implementation (Cookbook)

import json
import asyncio
import chz
from tinker_cookbook.rl import train
from tinker_cookbook.recipes.math_rl.math_env import Gsm8kDatasetBuilder
from tinker_cookbook import model_info

model_name = "meta-llama/Llama-3.1-8B"
renderer_name = model_info.get_recommended_renderer_name(model_name)
batch_size = 128
group_size = 16
max_tokens = 256

builder = Gsm8kDatasetBuilder(
    batch_size=batch_size,
    group_size=group_size,
    renderer_name=renderer_name,
    model_name_for_tokenizer=model_name,
)

blueprint = chz.Blueprint(train.Config).apply({
    "model_name": model_name,
    "log_path": "/tmp/rl-run",
    "dataset_builder": builder,
    "learning_rate": 4e-5,
    "max_tokens": max_tokens,
})

config = blueprint.make()
asyncio.run(train.main(config))

# --- Exact usage reporting (auto-captured by CLI) ---
# For RL: estimate from batch_size × group_size × max_tokens × num_batches
# The exact count comes from the training loop — check /tmp/rl-run for logs
import glob, os
log_files = sorted(glob.glob("/tmp/rl-run/metrics*.json"))
total_tokens = 0
for lf in log_files:
    with open(lf) as f:
        for line in f:
            m = json.loads(line)
            total_tokens += m.get("num_tokens", 0)
if total_tokens == 0:
    # Fallback estimate: batch_size × group_size × max_tokens × num_batches
    total_tokens = batch_size * group_size * max_tokens * 100
print(f'\n[OPENSCIENCE_USAGE] {json.dumps({"service": "tinker", "event_type": "training", "model": model_name, "tokens_used": total_tokens})}')

Custom RL with Low-Level API

For full control over sampling, reward computation, and advantage centering:

import json
import tinker
from tinker import types
from tinker.types.tensor_data import TensorData
import torch

model_name = "meta-llama/Llama-3.1-8B"
service_client = tinker.ServiceClient()
training_client = service_client.create_lora_training_client(
    base_model=model_name, rank=32
)

total_tokens = 0  # Track exact tokens for billing

for batch_idx, batch_rows in enumerate(dataset):
    path = training_client.save_weights_for_sampler(name=f"{batch_idx:06d}").result().path
    sampling_client = service_client.create_sampling_client(model_path=path)

    datums = []
    for question, answer in batch_rows:
        prompt = renderer.build_generation_prompt([{"role": "user", "content": question}])
        prompt_tokens = prompt.to_ints()
        result = sampling_client.sample(
            prompt=prompt, num_samples=16,
            sampling_params=types.SamplingParams(max_tokens=256, stop=renderer.get_stop_sequences()),
        ).result()

        rewards = [compute_reward(seq, answer) for seq in result.sequences]
        mean_reward = sum(rewards) / len(rewards)
        advantages = [r - mean_reward for r in rewards]
        if all(a == 0 for a in advantages):
            continue

        for seq, advantage in zip(result.sequences, advantages):
            tokens = prompt_tokens + seq.tokens
            ob_len = len(prompt_tokens) - 1
            datum = types.Datum(
                model_input=types.ModelInput.from_ints(tokens=tokens[:-1]),
                loss_fn_inputs={
                    "target_tokens": TensorData.from_torch(torch.tensor(tokens[1:])),
                    "logprobs": TensorData.from_torch(torch.tensor([0.0]*ob_len + list(seq.logprobs))),
                    "advantages": TensorData.from_torch(torch.tensor([0.0]*ob_len + [advantage]*(len(tokens)-1-ob_len))),
                },
            )
            datums.append(datum)

    # Track exact token count from datums
    total_tokens += sum(d.model_input.length() for d in datums)

    fwd_bwd = training_client.forward_backward(datums, loss_fn="importance_sampling")
    optim = training_client.optim_step(types.AdamParams(learning_rate=4e-5))
    fwd_bwd.result(); optim.result()

# --- Exact usage reporting (auto-captured by CLI) ---
print(f'\n[OPENSCIENCE_USAGE] {json.dumps({"service": "tinker", "event_type": "training", "model": model_name, "tokens_used": total_tokens})}')

Available RL Loss Functions

Available Models

Model Selection Tips:

• Cost efficiency: MoE models (Qwen3-30B-A3B at $0.36/M)
• Experimentation: Start with 8B models
• Vision tasks: Qwen3-VL-30B-A3B-Instruct
• Reasoning: Hybrid or Reasoning models with chain-of-thought

LoRA Configuration

Tinker exclusively uses LoRA. Default rank: 32.

training_client = service_client.create_lora_training_client(
    base_model="Qwen/Qwen3-30B-A3B",
    rank=32,
    train_attn=True,
    train_mlp=True,
    seed=42,
)

Critical: LoRA needs 20-100x higher LR than full fine-tuning. Use tinker_cookbook.hyperparam_utils.get_lr() for recommended values.

Hyperparameter Guide

Workflow 3: DPO (Preference Learning)

Use this for aligning models with human preferences without a separate reward model.

Quick Start

python -m tinker_cookbook.recipes.preference.train \
    log_path=/tmp/dpo-experiment \
    model_name=meta-llama/Llama-3.2-1B \
    dataset=hhh \
    renderer_name=role_colon \
    learning_rate=1e-5 \
    dpo_beta=0.1

Key differences from SFT: Use lower LR (1e-5 to 1e-6), base model should be in-distribution with preference data.

Available datasets: hhh (Anthropic), helpsteer3 (NVIDIA), ultrafeedback

Full RLHF pipeline: See DPO & Preference Learning for the three-step SL → preference model → RL pipeline.

Evaluations

Inline (During Training)

Add evaluator_builders to config for periodic evaluation:

blueprint = chz.Blueprint(train.Config).apply({
    ...
    "evaluator_builders": [my_evaluator],
    "eval_every": 8,
})

Offline (After Training)

MODEL_PATH=tinker://YOUR_MODEL_PATH_HERE
python -m tinker_cookbook.eval.run_inspect_evals \
    model_path=$MODEL_PATH \
    model_name=MODEL_NAME \
    tasks=inspect_evals/ifeval,inspect_evals/mmlu_0_shot

See Evaluations for custom evaluators and LLM-as-judge.

Cost Estimation & Usage Tracking

Pre-Training Cost Estimation

ALWAYS estimate cost before starting Tinker training. Load the tinker-training-cost skill and use its pricing tables or calculate manually:

Training Cost = (total_tokens × epochs × train_price_per_million) / 1,000,000

Present the cost estimate to the user for approval before starting training.

Automatic Usage Reporting (Ground Truth)

CRITICAL: All training scripts MUST print a [OPENSCIENCE_USAGE] line at the end. The CLI automatically captures this and reports exact billing to the dashboard.

# Add this at the END of every training script:
import json
print(f'\n[OPENSCIENCE_USAGE] {json.dumps({"service": "tinker", "event_type": "training", "model": model_name, "tokens_used": total_tokens})}')

How token counting works per workflow:

• Cookbook SFT: Tokenize dataset with get_tokenizer(model_name), multiply by num_epochs
• Cookbook RL: Parse training logs for num_tokens, or estimate from batch_size × group_size × max_tokens × batches
• Low-level API: Sum datum.model_input.length() across all forward_backward() calls

The CLI bash tool scans output for [OPENSCIENCE_USAGE] markers and auto-reports to the dashboard — no manual reporting needed.

Common Issues

Saving and Resuming

sampling_path = training_client.save_weights_for_sampler(name="final").result().path
sampling_client = service_client.create_sampling_client(model_path=sampling_path)

resume_path = training_client.save_state(name="checkpoint").result().path
training_client.load_state(resume_path)

Common Imports

import tinker
from tinker import types
from tinker.types import Datum, ModelInput, TensorData, AdamParams, SamplingParams

import chz
import asyncio
from tinker_cookbook.supervised import train
from tinker_cookbook.supervised.types import ChatDatasetBuilder, ChatDatasetBuilderCommonConfig
from tinker_cookbook.supervised.data import (
    SupervisedDatasetFromHFDataset,
    StreamingSupervisedDatasetFromHFDataset,
    FromConversationFileBuilder,
    conversation_to_datum,
)
from tinker_cookbook.renderers import get_renderer, TrainOnWhat
from tinker_cookbook.model_info import get_recommended_renderer_name
from tinker_cookbook.tokenizer_utils import get_tokenizer

External Resources

• Documentation: https://tinker-docs.thinkingmachines.ai/
• Cookbook Repo: https://github.com/thinking-machines-lab/tinker-cookbook
• Console: https://tinker-console.thinkingmachines.ai