LLMClient - Typescript/JS Library to build with LLMs

JS/TS library to make to easy to build with LLMs. Full support for various LLMs and VectorDBs, Agents, Function Calling, Chain-of-Thought, RAG, Semantic Router and more. Based on the popular Stanford DSP paper. Create and compose efficient prompts using prompt signatures. 🌡 πŸ¦™ πŸ”₯ ❀️ πŸ––πŸΌ

NPM Package Twitter Discord Chat


Build with prompt signatures

LLMClient is an easy to use library build around "Prompt Signatures" from the Stanford DSP paper. This library will automatically generate efficient and typed prompts from prompt signatures like question:string -> answer:string.

Build powerful workflows using components like RAG, ReAcT, Chain of Thought, Function calling, Agents, etc all built on prompt signatures and easy to compose together to build whatever you want. Using prompt signatures automatically gives you the ability to fine tune your prompt programs using optimizers. Tune with a larger model and have your program run efficiently on a smaller model. The tuning here is not the traditional model tuning but what we call prompt tuning.

Why use LLMClient?

  • Support for various LLMs and Vector DBs
  • Prompts auto-generated from simple signatures
  • Multi-Hop RAG, ReAcT, CoT, Function Calling and more
  • Build Agents that can call other agents
  • Convert docs of any format to text
  • RAG, smart chunking, embedding, querying
  • Automatic prompt tuning using optimizers
  • Production ready Typescript code
  • Almost zero-dependencies

Whats a prompt signature?

shapes at 24-03-31 00 05 55

Efficient type-safe prompts are auto-generated from a simple signature. A prompt signature is made of a "task description" inputField:type "field description" -> outputField:type". The idea behind prompt signatures is based off work done in the "Demonstrate-Search-Predict" paper.

You can have multiple input and output fields and each field has one of these types string, number, boolean, json or a array of any of these eg. string[]. When a type is not defined it defaults to string. When the json type if used the underlying AI is encouraged to generate correct JSON.

LLM's Supported

Provider Best Models Tested
OpenAI GPT: 4o, 4T, 4, 3.5 🟒 100%
Azure OpenAI GPT: 4, 4T, 3.5 🟒 100%
Together Several OSS Models 🟒 100%
Cohere CommandR, Command 🟒 100%
Anthropic Claude 2, Claude 3 🟒 100%
Mistral 7B, 8x7B, S, M & L 🟒 100%
Groq Lama2-70B, Mixtral-8x7b 🟒 100%
DeepSeek Chat and Code 🟒 100%
Ollama All models 🟒 100%
Google Vertex Palm, Bison 🟑 50%
Google Gemini Gemini 1.0 🟑 50%
Hugging Face OSS Model 🟑 50%

Example: Using chain-of-thought to summarize text

import { AI, ChainOfThought, OpenAIArgs } from 'llmclient';

const textToSummarize = `
The technological singularityβ€”or simply the singularity[1]β€”is a hypothetical future point in time at which technological growth becomes uncontrollable and irreversible, resulting in unforeseeable changes to human civilization.[2][3] ...`;

const ai = AI('openai', { apiKey: process.env.OPENAI_APIKEY } as OpenAIArgs);
const gen = new ChainOfThought(
`textToSummarize -> shortSummary "summarize in 5 to 10 words"`
const res = await gen.forward({ textToSummarize });

console.log('>', res);

Example: Building an agent

Use the agent prompt (framework) to build agents that work with other agents to complete tasks. Agents are easy to build with prompt signatures. Try out the agent example.

# npm run tsx ./src/examples/agent.ts

const researcher = new Agent(ai, {
name: 'researcher',
description: 'Researcher agent',
signature: `physicsQuestion "physics questions" -> answer "reply in bullet points"`

const summarizer = new Agent(ai, {
name: 'summarizer',
description: 'Summarizer agent',
signature: `text "text so summarize" -> shortSummary "summarize in 5 to 10 words"`

const agent = new Agent(ai, {
name: 'agent',
description: 'A an agent to research complex topics',
signature: `question -> answer`,
agents: [researcher, summarizer]

agent.forward({ questions: "How many atoms are there in the universe" })

Fast LLM Router

A special router that uses no LLM calls only embeddings to route user requests smartly.

Use the Router to efficiently route user queries to specific routes designed to handle certain types of questions or tasks. Each route is tailored to a particular domain or service area. Instead of using a slow or expensive LLM to decide how input from the user should be handled use our fast "Semantic Router" that uses inexpensive and fast embedding queries.

# npm run tsx ./src/examples/routing.ts

const customerSupport = new Route('customerSupport', [
'how can I return a product?',
'where is my order?',
'can you help me with a refund?',
'I need to update my shipping address',
'my product arrived damaged, what should I do?'

const technicalSupport = new Route('technicalSupport', [
'how do I install your software?',
'I’m having trouble logging in',
'can you help me configure my settings?',
'my application keeps crashing',
'how do I update to the latest version?'

const ai = AI('openai', { apiKey: process.env.OPENAI_APIKEY } as OpenAIArgs);

const router = new Router(ai);
await router.setRoutes(
[customerSupport, technicalSupport],
{ filename: 'router.json' }

const tag = await router.forward('I need help with my order');

if (tag === "customerSupport") {
if (tag === "technicalSupport") {

Vector DBs Supported

Vector databases are critical to building LLM workflows. We have clean abstractions over popular vector db's as well as our own quick in memory vector database.

Provider Tested
In Memory 🟒 100%
Weaviate 🟒 100%
Cloudflare 🟑 50%
Pinecone 🟑 50%
// Create embeddings from text using an LLM
const ret = await this.ai.embed({ texts: 'hello world' });

// Create an in memory vector db
const db = new DB('memory');

// Insert into vector db
await this.db.upsert({
id: 'abc',
table: 'products',
values: ret.embeddings[0]

// Query for similar entries using embeddings
const matches = await this.db.query({
table: 'products',
values: embeddings[0]

Alternatively you can use the DBManager which handles smart chunking, embedding and querying everything for you, it makes things almost too easy.

const manager = new DBManager({ ai, db });
await manager.insert(text);

const matches = await manager.query(
'John von Neumann on human intelligence and singularity.'

RAG Documents

Using documents like PDF, DOCX, PPT, XLS, etc with LLMs is a huge pain. We make it easy with the help of Apache Tika an open source document processing engine.

Launch Apache Tika

docker run -p 9998:9998 apache/tika

Convert documents to text and embed them for retrieval using the DBManager it also supports a reranker and query rewriter. Two default implementations DefaultResultReranker and DefaultQueryRewriter are available to use.

const tika = new ApacheTika();
const text = await tika.convert('/path/to/document.pdf');

const manager = new DBManager({ ai, db });
await manager.insert(text);

const matches = await manager.query('Find some text');

Tuning the prompts (programs)

You can tune your prompts using a larger model to help them run more efficiently and give you better results. This is done by using an optimizer like BootstrapFewShot with and examples from the popular HotPotQA dataset. The optimizer generates demonstrations demos which when used with the prompt help improve its efficiency.

// Download the HotPotQA dataset from huggingface
const hf = new HFDataLoader();
const examples = await hf.getData<{ question: string; answer: string }>({
dataset: 'hotpot_qa',
split: 'train',
count: 100,
fields: ['question', 'answer']

const ai = AI('openai', { apiKey: process.env.OPENAI_APIKEY } as OpenAIArgs);

// Setup the program to tune
const program = new ChainOfThought<{ question: string }, { answer: string }>(
`question -> answer "in short 2 or 3 words"`

// Setup a Bootstrap Few Shot optimizer to tune the above program
const optimize = new BootstrapFewShot<{ question: string }, { answer: string }>(

// Setup a evaluation metric em, f1 scores are a popular way measure retrieval performance.
const metricFn: MetricFn = ({ prediction, example }) =>
emScore(prediction.answer as string, example.answer as string);

// Run the optimizer and save the result
await optimize.compile(metricFn, { filename: 'demos.json' });

And to use the generated demos with the above ChainOfThought program

const ai = AI('openai', { apiKey: process.env.OPENAI_APIKEY } as OpenAIArgs);

// Setup the program to use the tuned data
const program = new ChainOfThought<{ question: string }, { answer: string }>(
`question -> answer "in short 2 or 3 words"`

// load tuning data

const res = await program.forward({
question: 'What castle did David Gregory inherit?'


Checkout more examples

Use the tsx command to run the examples it makes node run typescript code. It also support using a .env file to pass the AI API Keys as opposed to putting them in the commandline.

OPENAI_APIKEY=openai_key npm run tsx ./src/examples/marketing.ts
Example Description
customer-support.ts Extract valuable details from customer communications
food-search.ts Use multiple APIs are used to find dinning options
marketing.ts Generate short effective marketing sms messages
vectordb.ts Chunk, embed and search text
fibonacci.ts Use the JS code interpreter to compute fibonacci
summarize.ts Generate a short summary of a large block of text
chain-of-thought.ts Use chain-of-thought prompting to answer questions
rag.ts Use multi-hop retrieval to answer questions
rag-docs.ts Convert PDF to text and embed for rag search
react.ts Use function calling and reasoning to answer questions
agent.ts Agent framework, agents can use other agents, tools etc
qna-tune.ts Use an optimizer to improve prompt efficiency
qna-use-tuned.ts Use the optimized tuned prompts

Reasoning + Function Calling

Often you need the LLM to reason through a task and fetch and update external data related to this task. This is where reasoning meets function (API) calling. It's built-in so you get all of the magic automatically. Just define the functions you wish to you, a schema for the response object and thats it.

There are even some useful built-in functions like a Code Interpreter that the LLM can use to write and execute JS code.

We support providers like OpenAI that offer multiple parallel function calling and the standard single function calling.

Built-in Functions

Function Description
Code Interpreter Used by the LLM to execute JS code in a sandboxed env.
Embeddings Adapter Wrapper to fetch and pass embedding to your function

Our Goal

Large language models (LLMs) are getting really powerful and have reached a point where they can work as the backend for your entire product. However there is still a lot of manage a lot of complexity to manage from using the right prompts, models, etc. Our goal is to package all this complexity into a well maintained easy to use library that can work with all the LLMs out there. Additionally we are using the latest research to add useful new capabilities like DSP to the library.

How to use this library?

1. Pick an AI to work with

// Pick a LLM
const ai = new OpenAI({ apiKey: process.env.OPENAI_APIKEY } as OpenAIArgs);

2. Pick a memory for storing context (optional)

// Can be sub classed to build you own memory backends
const mem = new Memory();

3. Pick a prompt based on your usecase

const cot = new ChainOfThought(ai, `question:string -> answer:string`, { mem });

4. Use the prompt

const res = await cot.forward({ question: 'Are we in a simulation?' });

5. Alternatively use the LLM directly.

const res = await ai.chat([
{ role: "system", content: "Help the customer with his questions" }
{ role: "user", content: "I'm looking for a Macbook Pro M2 With 96GB RAM?" }

How do you use function calling

1. Define the functions

// define one or more functions and a function handler
const functions = [
name: 'getCurrentWeather',
description: 'get the current weather for a location',
parameters: {
type: 'object',
properties: {
location: {
type: 'string',
description: 'location to get weather for'
units: {
type: 'string',
enum: ['imperial', 'metric'],
default: 'imperial',
description: 'units to use'
required: ['location']
func: async (args: Readonly<{ location: string; units: string }>) => {
return `The weather in ${args.location} is 72 degrees`;

2. Pass the functions to a prompt

const cot = new ReAct(ai, `question:string -> answer:string`, { functions });

Enable debug logs

const ai = new OpenAI({ apiKey: process.env.OPENAI_APIKEY } as OpenAIArgs);
ai.setOptions({ debug: true });

Reach out

We're happy to help reach out if you have questions or join the Discord twitter/dosco


1. The LLM can't find the right function to use

Improve the function naming and description be very clear on what the function does. Also ensure the function parameter's also have good descriptions. The descriptions don't have to be very long but need to be clear.

2. How do I change the configuration of the LLM used

You can pass a configuration object as the second parameter when creating a new LLM object

const apiKey = process.env.OPENAI_APIKEY;
const conf = OpenAIBestConfig();
const ai = new OpenAI({ apiKey, conf } as OpenAIArgs);

3. My prompt is too long and can I change the max tokens

const conf = OpenAIDefaultConfig(); // or OpenAIBestOptions()
conf.maxTokens = 2000;

4. How do I change the model say I want to use GPT4

const conf = OpenAIDefaultConfig(); // or OpenAIBestOptions()
conf.model = OpenAIModel.GPT4Turbo;