anyllm-proxy/crates/translator

anyllm_translate

Pure, IO-free translation between Anthropic Messages API and OpenAI Chat Completions / Responses API formats. Also supports Google Gemini native API translation.

No HTTP clients, no async runtime, no network calls. Just fn(A) -> B transformations.

Quick Start

use anyllm_translate::{TranslationConfig, translate_request, translate_response};
use anyllm_translate::anthropic::MessageCreateRequest;

let config = TranslationConfig::builder()
    .model_map("haiku", "gpt-4o-mini")
    .model_map("sonnet", "gpt-4o")
    .model_map("opus", "gpt-4o")
    .build();

let req: MessageCreateRequest = serde_json::from_str(r#"{
    "model": "claude-sonnet-4-6",
    "max_tokens": 100,
    "messages": [{"role": "user", "content": "Hello"}]
}"#).unwrap();

let openai_req = translate_request(&req, &config).unwrap();
assert_eq!(openai_req.model, "gpt-4o");

// Send openai_req to OpenAI, get response, then:
// let anthropic_resp = translate_response(&openai_resp, &req.model);

Supported APIs

• Anthropic Messages API (request/response types, streaming SSE events)
• OpenAI Chat Completions API (request/response types, streaming chunks)
• OpenAI Responses API (request/response types, streaming events)
• Google Gemini native API (generateContent types, streaming)

Features

• Default: Pure translation types and mapping functions
• middleware: Adds an axum middleware layer that intercepts Anthropic-format requests, translates them, forwards to a configurable backend, and translates responses back

[dependencies]
anyllm_translate = "0.1"

# With middleware support:
anyllm_translate = { version = "0.1", features = ["middleware"] }

Modules

Module	Description
anthropic	Anthropic Messages API types (request, response, streaming, errors)
openai	OpenAI Chat Completions and Responses API types
gemini	Google Gemini native API types
mapping	Stateless conversion functions between APIs
config	Translation configuration (model mapping, lossy behavior)
translate	Convenience wrappers combining config with mapping
middleware	Axum middleware layer (requires middleware feature)

Translation Coverage

• Text messages, multi-turn conversations
• System prompts (Anthropic system to OpenAI developer role or Responses instructions)
• Tool definitions, tool calls, tool results
• Image and document content blocks (documents degrade to text notes)
• Streaming SSE event translation (state machines for each backend)
• Token usage mapping
• Error type/status code translation
• Extended thinking (stripped when targeting OpenAI)

Related

This crate is part of anyllm-proxy, which also includes a standalone HTTP proxy server.