llm-proxy

LLM Proxy

LLM Proxy is a lightweight HTTP service that forwards user prompts to OpenAI's Responses API, OpenAI-compatible chat providers, Google Gemini's native generateContent API, and audio transcription APIs. It exposes protected HTTP endpoints that require a shared secret and simplify integrating provider capabilities without embedding API credentials in each client.

Features

• Minimal HTTP server that accepts:
  • GET /?prompt=...&key=...[&provider=...] for LLM responses
  • POST /?key=...[&provider=...] for large JSON prompt bodies
  • POST /dictate?key=...[&provider=...] for audio transcription
• Choose the provider per request via provider=... (default: openai)
• Choose the model per request via model=... (default: gpt-4.1 for OpenAI)
• Choose the dictation model per request via model=... on /dictate (default: gpt-4o-mini-transcribe)
• Optional per-request OpenAI web search via web_search=1|true|yes
• Optional logging at debug or info levels
• Forwards requests using server-side provider API keys
• Supports plain text, JSON, XML, or CSV responses

Configuration

The service reads service configuration from config.yml. The default path is config.yml in the current working directory; use --config /path/config.yml only to select a different file. Command-line flags and environment variables are not service configuration sources.

Before parsing YAML, the loader expands ${NAME} placeholders from process environment variables and from an optional .env file in the same directory as the selected config file. Process environment values override .env values. Missing placeholders fail startup. The loader does not mutate process environment, and all runtime code receives only the validated config value.

server:
  service_secret: "${SERVICE_SECRET}"
  port: 8080
  log_level: info
  workers: 4
  queue_size: 100
  request_timeout_seconds: 180
  upstream_poll_timeout_seconds: 60
  max_prompt_bytes: 4194304
  max_input_audio_bytes: 26214400
defaults:
  provider: openai
  model: gpt-4.1
  dictation_provider: openai
  dictation_model: gpt-4o-mini-transcribe
  system_prompt: ""
providers:
  openai:
    api_key: "${OPENAI_API_KEY}"
  deepseek:
    api_key: ""
    base_url: ""
  dashscope:
    api_key: ""
    base_url: ""
  moonshot:
    api_key: ""
    base_url: ""
  siliconflow:
    api_key: ""
    base_url: ""
    transcriptions_url: ""
  zhipu:
    api_key: ""
    base_url: ""
  gemini:
    api_key: ""
    base_url: ""

Blank optional values use built-in provider defaults where applicable. Startup validates server.service_secret, the credential for defaults.provider, and the credential/endpoint support for defaults.dictation_provider. Credentials for non-default providers may stay blank; requests selecting those providers return 503 Service Unavailable until the corresponding api_key is configured. Unknown YAML keys fail startup.

Web search is per request and currently supported only on OpenAI models that support the OpenAI web search tool. Text output length is also per request: pass max_tokens when a client wants to cap one generation. When omitted, the proxy does not send a provider max-token field. Provider-specific output-token limits are enforced at the request edge when known. Gemini text models currently reject max_tokens above 65536 with 400 Bad Request before any upstream provider call.

Running

Generate a secret:

openssl rand -hex 32

Run the service with OpenAI defaults:

./llm-proxy --config config.yml

Run the service with DeepSeek as the default text provider:

defaults:
  provider: deepseek
providers:
  deepseek:
    api_key: "${DEEPSEEK_API_KEY}"

Run the service with Gemini as the default text provider:

defaults:
  provider: gemini
providers:
  gemini:
    api_key: "${GEMINI_API_KEY}"

Local Automation

This repository exposes the standard local targets used by MPR app repos:

The release lifecycle commands wrap their local make ci gate with the standard 350-second timeout by default. For exceptional local diagnostics, override all three with LLM_PROXY_CI_TIMEOUT_SECONDS=<seconds>, or use the command-specific RELEASE_CI_TIMEOUT_SECONDS, PUBLISH_CI_TIMEOUT_SECONDS, and DEPLOY_CI_TIMEOUT_SECONDS variables.

llm-proxy is a gateway-local service in mprlab-gateway, so make deploy defaults to the gateway deploy-gateway target. Override the checkout or target with GATEWAY_DIR=/path/to/mprlab-gateway or GATEWAY_DEPLOY_TARGET=<target>.

Usage

Installable prompt client

Install the reusable JSON POST client:

go install github.com/tyemirov/llm-proxy/llm-proxy-client@latest

Use it with explicit flags:

llm-proxy-client \
  --base-url "http://localhost:8080/?provider=gemini" \
  --secret "$SERVICE_SECRET" \
  --model gemini-3.5-flash \
  --prompt "Summarize this"

Or read configuration and prompt text from environment/stdin:

export LLM_PROXY_BASE_URL="http://localhost:8080/"
export LLM_PROXY_SECRET="$SERVICE_SECRET"
printf 'large prompt...\n' | llm-proxy-client --model gpt-5.5 --max-tokens 4096

The client always uses POST /?key=... with a JSON body. It keeps non-payload query parameters such as provider, strips body-owned query fields such as prompt and model, and sends prompt, model, web_search, system_prompt, and max_tokens in the body.

Python client package

The same transport contract is available as an importable Python package:

uv pip install "llm-proxy-client @ git+https://github.com/tyemirov/llm-proxy.git"

from llm_proxy_client import Client, ClientConfig, ClientRequest

client = Client(
    ClientConfig(
        base_url="http://localhost:8080/?provider=gemini",
        secret="mysecret",
    )
)
text = client.post(
    ClientRequest(
        prompt="Summarize this",
        model="gemini-3.5-flash",
        max_tokens=512,
    )
)

For local development:

uv pip install -e .
make python-test
make python-lint

Basic request (default provider and model, no web search)

curl --get \
  --data-urlencode "prompt=Hello, how are you?" \
  --data-urlencode "key=mysecret" \
  "http://localhost:8080/"

Choose a provider

curl --get \
  --data-urlencode "prompt=Summarize this cheaply" \
  --data-urlencode "key=mysecret" \
  --data-urlencode "provider=deepseek" \
  --data-urlencode "model=deepseek-v4-flash" \
  "http://localhost:8080/"

Gemini text generation:

curl --get \
  --data-urlencode "prompt=Summarize this with Gemini" \
  --data-urlencode "key=mysecret" \
  --data-urlencode "provider=gemini" \
  --data-urlencode "model=gemini-3.5-flash" \
  --data-urlencode "max_tokens=512" \
  "http://localhost:8080/"

Large text request

Use POST / with a JSON body when the prompt is too large for a URL query parameter. Authentication still uses the key query parameter, which is the configured server.service_secret. Provider selection also stays in the query parameter. Do not send upstream provider secrets in the request body; the proxy reads them from server-side configuration. The JSON body is capped by server.max_prompt_bytes.

curl -X POST \
  -H "Content-Type: application/json" \
  --data '{"prompt":"large text...","model":"gpt-5.5","web_search":false,"system_prompt":"optional","max_tokens":4096}' \
  "http://localhost:8080/?key=mysecret"

JSON body fields:

For POST /, provider remains a query parameter. Query model may override the JSON body only when the body omits model or provides the same value; conflicting values return 400 Bad Request. Gemini max_tokens values above 65536 return 400 Bad Request before the proxy calls Gemini.

Choose an OpenAI model

curl --get \
  --data-urlencode "prompt=Summarize quantum error correction" \
  --data-urlencode "key=mysecret" \
  --data-urlencode "model=gpt-4o" \
  "http://localhost:8080/"

Enable web search

curl --get \
  --data-urlencode "prompt=What changed in the 2025 child tax credit?" \
  --data-urlencode "key=mysecret" \
  --data-urlencode "web_search=1" \
  "http://localhost:8080/"

You can enable web search with GPT-5 by specifying the model:

curl --get \
  --data-urlencode "prompt=Latest research on quantum gravity" \
  --data-urlencode "key=mysecret" \
  --data-urlencode "model=gpt-5" \
  --data-urlencode "web_search=1" \
  "http://localhost:8080/"

Dictation request

curl -X POST \
  -F "audio=@./recording.webm" \
  "http://localhost:8080/dictate?key=mysecret"

SiliconFlow dictation:

curl -X POST \
  -F "audio=@./recording.webm" \
  "http://localhost:8080/dictate?key=mysecret&provider=siliconflow"

Optional model override:

curl -X POST \
  -F "audio=@./recording.webm" \
  "http://localhost:8080/dictate?key=mysecret&model=gpt-4o-mini-transcribe"

Response formats

You can request alternative formats using either the format query parameter or the Accept header. Supported values are:

• text/csv - the reply as a single CSV cell with internal quotes doubled and a trailing newline
• application/json - JSON object containing request and response fields, plus usage when upstream token usage is available
• application/xml - XML document <response request="...">...</response>

If no supported value is provided, text/plain is returned.

When upstream text providers return token usage, the proxy also sets these response headers without changing the plain text, XML, or CSV response bodies:

JSON-format LLM responses include the same normalized counts:

{
  "request": "Hello",
  "response": "Hi",
  "usage": {
    "request_tokens": 1,
    "response_tokens": 1,
    "total_tokens": 2
  }
}

Endpoint

LLM endpoint

GET /
  ?prompt=STRING            # required
  &key=SERVICE_SECRET       # required
  &provider=PROVIDER        # optional; defaults to openai
  &model=MODEL_NAME         # optional; provider default
  &web_search=1|true|yes    # optional; OpenAI web_search tool
  &max_tokens=N             # optional positive integer per-request cap
  &format=CONTENT_TYPE      # optional; or use Accept header

POST /
  ?key=SERVICE_SECRET       # required
  &provider=PROVIDER        # optional; defaults to openai
  &model=MODEL_NAME         # optional; overrides JSON body if absent or equal
  &format=CONTENT_TYPE      # optional; or use Accept header
Content-Type: application/json
{
  "prompt": "STRING",       # required
  "model": "MODEL_NAME",    # optional; provider default
  "web_search": false,      # optional; defaults to false
  "system_prompt": "STRING",# optional; defaults to configured system prompt
  "max_tokens": 512         # optional positive integer per-request cap
}

The POST JSON body carries only LLM request parameters. The client shared secret remains in the key query parameter, and upstream provider API keys are never accepted from client requests.

Dictation endpoint

POST /dictate
  ?key=SERVICE_SECRET       # required
  &provider=PROVIDER        # optional; defaults to openai
  &model=MODEL_NAME         # optional; provider default
Content-Type: multipart/form-data
  audio=<file>              # required (alias: file)

Success response:

{ "text": "..." }

Supported LLM endpoint models are listed below. The /dictate endpoint defaults to OpenAI's audio transcriptions API and supports SiliconFlow when provider=siliconflow. Not all models support tools; use a model marked Yes below for web search.

Model capabilities

Status codes

• 200 OK - success
• 400 Bad Request - missing/invalid parameters, invalid multipart audio form, unknown provider/model, or unsupported provider capability
• 403 Forbidden - missing or invalid key
• 413 Payload Too Large - JSON prompt body exceeds max_prompt_bytes
• 429 Too Many Requests - upstream provider rate limit
• 503 Service Unavailable - selected provider is not configured server-side
• 504 Gateway Timeout - upstream request timed out
• 502 Bad Gateway - upstream provider API returned an error

Security

• All requests must include the shared secret via key=....
• Client requests must not include upstream provider API keys; configure them on the server.
• Do not expose this service to the public internet without appropriate network controls.

Implementation Plans

Current scoped implementation plans are tracked under docs/implementation/.

MPR Integration Verification

For Marco Polo Research Lab integration workflows, use the Codex mpr-integration skill when a change needs contract/profile/task-based black-box verification against an MPR app or fixture. Keep app-specific hostnames, cookie names, ports, OAuth callbacks, and environment literals in the selected integration profile or deployment docs, not in this README.

Releasing

Use make release from a clean, up-to-date master branch. It runs make ci, updates CHANGELOG.md if the selected version is missing, creates the release commit when needed, and pushes the v* tag. Tags that begin with v trigger the release workflow, which builds and publishes release artifacts and uses the matching changelog section as release notes.

Use make publish only when you need to publish the release image manually. Use make deploy after the release image is published and :latest points at the same digest as the release tag.

License

This project is licensed under the MIT License. See LICENSE for details.