Create a trainer

POST

loops

trainers

cURL

curl --request POST \
--url https://api.baseten.co/v1/loops/trainers \
--header "Authorization: Bearer $BASETEN_API_KEY" \
--data '{
  "session_id": null,
  "base_model": null,
  "name": null,
  "max_seq_len": null,
  "seed": null,
  "path": "bt://loops:k4q95w5/weights/step-100",
  "reuse_from_run_id": null,
  "reuse_from_session_id": null
}'

import requests
import os
API_KEY = os.environ.get("BASETEN_API_KEY", "<YOUR_API_KEY>")
url = "https://api.baseten.co/v1/loops/trainers"

headers = {"Authorization": f"Bearer {API_KEY}"}

response = requests.request(
    "POST",
    url,
    headers=headers,
    json={'session_id': None, 'base_model': None, 'name': None, 'max_seq_len': None, 'seed': None, 'path': 'bt://loops:k4q95w5/weights/step-100', 'reuse_from_run_id': None, 'reuse_from_session_id': None}
)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    session_id: '<string>',
    base_model: '<string>',
    name: '<string>',
    max_seq_len: 123,
    lora_rank: 64,
    seed: 123,
    scale_down_delay_seconds: 3600,
    replicas: 1,
    path: 'bt://loops:k4q95w5/weights/step-100',
    reuse_from_run_id: '<string>',
    reuse_from_session_id: '<string>'
  })
};

fetch('https://api.baseten.co/v1/loops/trainers', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.baseten.co/v1/loops/trainers",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'session_id' => '<string>',
    'base_model' => '<string>',
    'name' => '<string>',
    'max_seq_len' => 123,
    'lora_rank' => 64,
    'seed' => 123,
    'scale_down_delay_seconds' => 3600,
    'replicas' => 1,
    'path' => 'bt://loops:k4q95w5/weights/step-100',
    'reuse_from_run_id' => '<string>',
    'reuse_from_session_id' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.baseten.co/v1/loops/trainers"

	payload := strings.NewReader("{\n  \"session_id\": \"<string>\",\n  \"base_model\": \"<string>\",\n  \"name\": \"<string>\",\n  \"max_seq_len\": 123,\n  \"lora_rank\": 64,\n  \"seed\": 123,\n  \"scale_down_delay_seconds\": 3600,\n  \"replicas\": 1,\n  \"path\": \"bt://loops:k4q95w5/weights/step-100\",\n  \"reuse_from_run_id\": \"<string>\",\n  \"reuse_from_session_id\": \"<string>\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.baseten.co/v1/loops/trainers")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"session_id\": \"<string>\",\n  \"base_model\": \"<string>\",\n  \"name\": \"<string>\",\n  \"max_seq_len\": 123,\n  \"lora_rank\": 64,\n  \"seed\": 123,\n  \"scale_down_delay_seconds\": 3600,\n  \"replicas\": 1,\n  \"path\": \"bt://loops:k4q95w5/weights/step-100\",\n  \"reuse_from_run_id\": \"<string>\",\n  \"reuse_from_session_id\": \"<string>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.baseten.co/v1/loops/trainers")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"session_id\": \"<string>\",\n  \"base_model\": \"<string>\",\n  \"name\": \"<string>\",\n  \"max_seq_len\": 123,\n  \"lora_rank\": 64,\n  \"seed\": 123,\n  \"scale_down_delay_seconds\": 3600,\n  \"replicas\": 1,\n  \"path\": \"bt://loops:k4q95w5/weights/step-100\",\n  \"reuse_from_run_id\": \"<string>\",\n  \"reuse_from_session_id\": \"<string>\"\n}"

response = http.request(request)
puts response.read_body

{
  "run": {
    "id": "<string>",
    "session_id": "<string>",
    "deployment_id": "<string>",
    "name": "<string>",
    "base_model": "<string>",
    "base_url": "<string>",
    "created_at": "2023-11-07T05:31:56Z",
    "status": {},
    "user": {
      "email": "<string>"
    },
    "sampler": {
      "id": "<string>",
      "base_url": "<string>",
      "base_model": "<string>",
      "created_at": "2023-11-07T05:31:56Z",
      "model_id": "<string>",
      "deployment_id": "<string>",
      "status": {},
      "user": {
        "email": "<string>"
      },
      "instance_type": {
        "id": "<string>",
        "name": "<string>",
        "memory_limit_mib": 123,
        "millicpu_limit": 123,
        "gpu_count": 123,
        "gpu_type": "<string>",
        "gpu_memory_limit_mib": 123
      },
      "node_count": 1
    }
  }
}

Authorizations

Authorization

string

header

required

Send Authorization: Bearer <api_key>. The legacy Authorization: Api-Key <api_key> scheme is also accepted.

Body

application/json

session_id

string

required

ID of the Loops session this run belongs to.

base_model

string

required

Base model ID (e.g. 'Qwen/Qwen3-8B').

name

string | null

Optional display name for the run. Defaults to the base model name when omitted.

Required string length: 1 - 255

max_seq_len

integer | null

Maximum prompt length (in tokens) the run must handle. Set this to the longest training example you plan to send. Defaults to the maximum supported by the model configuration.

lora_rank

integer

default:64

LoRA rank.

Required range: x >= 1

seed

integer | null

Random seed for reproducibility.

scale_down_delay_seconds

integer

default:3600

Seconds of inactivity before the run scales to zero. Must be between 1 and 3600 (1 hour). Defaults to 3600.

Required range: x <= 3600

replicas

integer

default:1

Number of data-parallel trainer replicas. Each replica is one full copy of the model's preset node group, so the trainer deployment runs (preset node_count * replicas) nodes (e.g. replicas=4 on a 4-node preset → 16 nodes, 4 DP workers). Must be a positive integer. Defaults to 1.

Required range: x >= 1

path

string | null

Optional bt:// URI of an existing checkpoint to load weights from on startup. Form: bt://loops:<run_id>/weights/<checkpoint_name>.

Example:

"bt://loops:k4q95w5/weights/step-100"

reuse_from_run_id

string | null

Optional ID of a prior Loops run whose trainer and/or sampler should be reused for this run instead of provisioning fresh. The prior run must use the same base model and belong to the same team.

reuse_from_session_id

string | null

Optional ID of a prior Loops session whose trainer and/or sampler should be reused for this run. Deprecated in favor of reuse_from_run_id.

Response

200 - application/json

run

LoopsRunV1 · object

required

Show child attributes

Create a team trainerCreates a trainer-only Loops run in the given session, without a sampler. To sample from it, create a sampler with POST /v1/loops/samplers and pass this run's ID as run_id to pair the two. List and read the trainer through the /v1/loops/runs endpoints.

⌘I

cURL

curl --request POST \
--url https://api.baseten.co/v1/loops/trainers \
--header "Authorization: Bearer $BASETEN_API_KEY" \
--data '{
  "session_id": null,
  "base_model": null,
  "name": null,
  "max_seq_len": null,
  "seed": null,
  "path": "bt://loops:k4q95w5/weights/step-100",
  "reuse_from_run_id": null,
  "reuse_from_session_id": null
}'

import requests
import os
API_KEY = os.environ.get("BASETEN_API_KEY", "<YOUR_API_KEY>")
url = "https://api.baseten.co/v1/loops/trainers"

headers = {"Authorization": f"Bearer {API_KEY}"}

response = requests.request(
    "POST",
    url,
    headers=headers,
    json={'session_id': None, 'base_model': None, 'name': None, 'max_seq_len': None, 'seed': None, 'path': 'bt://loops:k4q95w5/weights/step-100', 'reuse_from_run_id': None, 'reuse_from_session_id': None}
)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    session_id: '<string>',
    base_model: '<string>',
    name: '<string>',
    max_seq_len: 123,
    lora_rank: 64,
    seed: 123,
    scale_down_delay_seconds: 3600,
    replicas: 1,
    path: 'bt://loops:k4q95w5/weights/step-100',
    reuse_from_run_id: '<string>',
    reuse_from_session_id: '<string>'
  })
};

fetch('https://api.baseten.co/v1/loops/trainers', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.baseten.co/v1/loops/trainers",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'session_id' => '<string>',
    'base_model' => '<string>',
    'name' => '<string>',
    'max_seq_len' => 123,
    'lora_rank' => 64,
    'seed' => 123,
    'scale_down_delay_seconds' => 3600,
    'replicas' => 1,
    'path' => 'bt://loops:k4q95w5/weights/step-100',
    'reuse_from_run_id' => '<string>',
    'reuse_from_session_id' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.baseten.co/v1/loops/trainers"

	payload := strings.NewReader("{\n  \"session_id\": \"<string>\",\n  \"base_model\": \"<string>\",\n  \"name\": \"<string>\",\n  \"max_seq_len\": 123,\n  \"lora_rank\": 64,\n  \"seed\": 123,\n  \"scale_down_delay_seconds\": 3600,\n  \"replicas\": 1,\n  \"path\": \"bt://loops:k4q95w5/weights/step-100\",\n  \"reuse_from_run_id\": \"<string>\",\n  \"reuse_from_session_id\": \"<string>\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.baseten.co/v1/loops/trainers")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"session_id\": \"<string>\",\n  \"base_model\": \"<string>\",\n  \"name\": \"<string>\",\n  \"max_seq_len\": 123,\n  \"lora_rank\": 64,\n  \"seed\": 123,\n  \"scale_down_delay_seconds\": 3600,\n  \"replicas\": 1,\n  \"path\": \"bt://loops:k4q95w5/weights/step-100\",\n  \"reuse_from_run_id\": \"<string>\",\n  \"reuse_from_session_id\": \"<string>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.baseten.co/v1/loops/trainers")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"session_id\": \"<string>\",\n  \"base_model\": \"<string>\",\n  \"name\": \"<string>\",\n  \"max_seq_len\": 123,\n  \"lora_rank\": 64,\n  \"seed\": 123,\n  \"scale_down_delay_seconds\": 3600,\n  \"replicas\": 1,\n  \"path\": \"bt://loops:k4q95w5/weights/step-100\",\n  \"reuse_from_run_id\": \"<string>\",\n  \"reuse_from_session_id\": \"<string>\"\n}"

response = http.request(request)
puts response.read_body

{
  "run": {
    "id": "<string>",
    "session_id": "<string>",
    "deployment_id": "<string>",
    "name": "<string>",
    "base_model": "<string>",
    "base_url": "<string>",
    "created_at": "2023-11-07T05:31:56Z",
    "status": {},
    "user": {
      "email": "<string>"
    },
    "sampler": {
      "id": "<string>",
      "base_url": "<string>",
      "base_model": "<string>",
      "created_at": "2023-11-07T05:31:56Z",
      "model_id": "<string>",
      "deployment_id": "<string>",
      "status": {},
      "user": {
        "email": "<string>"
      },
      "instance_type": {
        "id": "<string>",
        "name": "<string>",
        "memory_limit_mib": 123,
        "millicpu_limit": 123,
        "gpu_count": 123,
        "gpu_type": "<string>",
        "gpu_memory_limit_mib": 123
      },
      "node_count": 1
    }
  }
}

Reference

Inference API

Management API

CLI reference

SDK reference

Training API

Frontier Gateway API

CI/CD

Create a trainer

Authorizations

Body

Response