Why did we open-source our inference engine? Read the post

Pay 36% less than GPT-6.1 Sol and keep 95% of its quality

Send each request to a cheap model when it can answer well, and to a strong model only when it needs one. SIE, an open-source inference engine, serves Qwen3 Reranker 4B, the open model that decides: one call scores each request against a one-line description of what your cheap model handles, and your threshold picks the model.

SIE Qwen3 Reranker 4B

Sent to GPT-6 Luna
Request

Solve for x: x/2 + x/3 = 5

GPT-6 Luna's answer

x = 6

An LLM as your router cuts the bill by 1.4% at best

GPT-6 Luna as the router (no reasoning)

Bill went up 0.7%
Moved from GPT-⁠6.1 Sol to GPT-⁠6 Luna
0 of the 728 requests it rated

Claude Haiku 5.5 as the router (thinking off)

Cut the bill by only 1.4%
Moved from Claude Sonnet 5.5 to Claude Haiku 5.5
116 of the 728 requests it rated

95% of GPT-⁠6.1 Sol's quality for 36% less, each route decided 106x faster than GPT-⁠6 Luna

Quality kept
share of GPT-6.1 Sol's ↑
Always GPT-6.1 Sol
Always GPT-6.1 Sol 100%
GPT-6 Luna as the router
GPT-6 Luna as the router 100%
SIE Qwen3 Reranker 4B
SIE Qwen3 Reranker 4B 95.9%
Always GPT-6 Luna
Always GPT-6 Luna 80.9%
Time per routing decision
median ↓
SIE Qwen3 Reranker 4B
8.5 ms SIE Qwen3 Reranker 4B
GPT-6 Luna as the router
GPT-6 Luna as the router 904 ms
Cost per 1,000 requests
USD ↓
Always GPT-6 Luna
$0.42 Always GPT-6 Luna
SIE Qwen3 Reranker 4B
SIE Qwen3 Reranker 4B $3.31
Always GPT-6.1 Sol
Always GPT-6.1 Sol $5.19
GPT-6 Luna as the router
GPT-6 Luna as the router $5.23
Tested
728 held-out requests: hard science questions, math, Python tasks and open chat
Scored
Graded answers; open chat judged by the other provider's strong model
Prices
List prices on 11 Oct 2026, routing call included
Timing
SIE timed on a GPU server with the client alongside; rivals over their public APIs

One score call decides the route

from sie_sdk import SIEClient
​
client = SIEClient(api_key="API keysk-sie-…")
​
query = "queryA request that a small, cheap AI model can answer correctly."
document = "document 1Solve the following math problem. Put your final answer within \boxed{}. Solve for $x$: $\frac{x}2 + \frac{x}3 = 5$"
score = client.score(
"modelQwen/Qwen3-Reranker-4B",
{"text": query},
[{"id": "0", "text": document}],
instruction="instructionJudge whether the Document, a request sent to an AI assistant, fits the description in the Query.",
)["scores"][0]["score"]
print(score)
import { SIEClient } from '@superlinked/sie-sdk';

const client = new SIEClient(undefined, { apiKey: 'sk-sie-…' });

const query = "A request that a small, cheap AI model can answer correctly.";
const document = "Solve the following math problem. Put your final answer within \\boxed{}.\n\nSolve for $x$: $\\frac{x}2 + \\frac{x}3 = 5$";
const ranked = await client.score(
  'Qwen/Qwen3-Reranker-4B',
  { text: query },
  [{ id: '0', text: document }],
  { instruction: "Judge whether the Document, a request sent to an AI assistant, fits the description in the Query." },
);
console.log(ranked.scores[0].score);
curl https://api.superlinked.com/v1/score/Qwen%2FQwen3-Reranker-4B \
  -H "Authorization: Bearer sk-sie-…" \
  -H "Content-Type: application/json" \
  -d "{\"query\":{\"text\":\"A request that a small, cheap AI model can answer correctly.\"},\"items\":[{\"id\":\"0\",\"text\":\"Solve the following math problem. Put your final answer within \\\\boxed{}.\\n\\nSolve for \$x\$: \$\\\\frac{x}2 + \\\\frac{x}3 = 5\$\"}],\"instruction\":\"Judge whether the Document, a request sent to an AI assistant, fits the description in the Query.\"}"
Build the "Score a request against a description" capability into my app using the Superlinked Inference Engine (SIE).

Context
- SIE is an OpenAI-style inference API. Python SDK: `from sie_sdk import SIEClient`; TypeScript: `@superlinked/sie-sdk`.
- Base URL: https://api.superlinked.com (or my regional endpoint). Auth: Bearer key from env `SIE_API_KEY` (never hard-code it).
- Model: Qwen/Qwen3-Reranker-4B (SIE primitive: /score). Keep the model id configurable.

Task
- Input: a one-line description (the query) plus one request to score against it.
- Behaviour: score the one request against the description and return that one score.
- Send one POST https://api.superlinked.com/v1/score/Qwen%2FQwen3-Reranker-4B request (SDK: score) with the description as the query, the request as the only item and the instruction below. Read the one score from scores[0].score. Do not batch requests or rank anything. Instruction, sent as given: "Judge whether the Document, a request sent to an AI assistant, fits the description in the Query."

Deliverables
- A typed client wrapper, an application-level function for this task, error handling for timeouts/empty input, and unit tests with a stubbed client.
- Wire it into my existing stack (ask me which framework if unclear) and add a short usage example.
Output

scores[0].score

0.114

Pay 36% less than always using GPT-6.1 Sol

Self-hosted (Kubernetes)

SIE in your clusters, backed by our engineers.

  • Data stays in your own cloud account
  • Same models and API as Serverless
  • Terraform to your cloud in minutes

Run locally

The open-source server on your own machine.

docker run --gpus all -p 8080:8080 ghcr.io/superlinked/sie-server:latest-cuda12-default

Switch to SIE in 5 minutes

import json
from openai import OpenAI

openai = OpenAI()

rating = openai.responses.create(
    model="gpt-6-luna",
    instructions=rating_prompt,
    input=request,
    reasoning={"effort": "none"},
    text={"format": rating_format},
)
score = json.loads(rating.output_text)["score"]

model = "gpt-6-luna" if score >= threshold else "gpt-6.1-sol"
import json
from anthropic import Anthropic

anthropic = Anthropic()

rating = anthropic.messages.create(
    model="claude-haiku-5-5",
    system=rating_prompt,
    messages=[{"role": "user", "content": request}],
    thinking={"type": "disabled"},
    output_config={"format": rating_format},
    max_tokens=64,
)
score = json.loads(rating.content[0].text)["score"]

model = "claude-haiku-5-5" if score >= threshold else "claude-sonnet-5-5"
SIE
from sie_sdk import SIEClient

client = SIEClient(api_key="sk-sie-…")

score = client.score(
    "Qwen/Qwen3-Reranker-4B",
    {"text": cheap_model_handles},
    [{"id": "request", "text": request}],
    instruction=routing_instruction,
)["scores"][0]["score"]

model = "gpt-6-luna" if score >= threshold else "gpt-6.1-sol"
from sie_sdk import SIEClient

client = SIEClient(api_key="sk-sie-…")

score = client.score(
    "Qwen/Qwen3-Reranker-4B",
    {"text": cheap_model_handles},
    [{"id": "request", "text": request}],
    instruction=routing_instruction,
)["scores"][0]["score"]

model = "claude-haiku-5-5" if score >= threshold else "claude-sonnet-5-5"

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