Welcome to the Blnk SDK for TypeScript Developer Guide. In this guide, you’ll learn how to install Blnk and work with our Blnk TypeScript SDK. To view the open-source file, see the following: Blnk TypeScript SDK. You’ll also find examples of running different fintech use cases with our TypeScript SDK.

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Prerequisites

Ensure that you have the following installed on your machine.
  1. Docker and Compose for running Blnk locally on your machine.
  2. Node.js (v14.0.0 or later) and npm for installing the Blnk Typescript SDK.

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1. Installation & Configuration

Once you’re good to go with the prerequisites, you can set up your Blnk server and SDK in 5 steps:
1

Clone the Blnk repository

Run the following command in your terminal to clone Blnk to your local machine:
bash
git clone https://github.com/blnkfinance/blnk && cd blnk
2

Set up your Blnk configuration

Create a blnk.json file in your blnk project folder, paste the following configuration settings, and save.
blnk.json
{
    "project_name": "Blnk",
    "data_source": {
        "dns": "postgres://postgres:password@postgres:5432/blnk?sslmode=disable"
    },
    "redis": {
        "dns": "redis:6379"
    },
    "server": {
        "domain": "blnk.io",
        "ssl": false,
        "ssl_email": "jerryenebeli@gmail.com",
        "port": "5001"
    },
    "notification": {
        "slack": {
        "webhook_url": "https://hooks.slack.com"
        }
    }
}
This configuration sets up the required connections to PostgreSQL and Redis, specifies your server details, and allows Slack notifications if needed.
3

Launch Blnk

Launch the Blnk server with the following command:
bash
docker compose up
Once running, your server will be accessible at http://localhost:5001.
4

Install Blnk CLI

The Blnk CLI helps you to quickly test and manage your Blnk backend directly from your command line. You can also use it to perform create actions or view your data tables. To install and use the Blnk CLI, see the following in: Installing the Blnk CLI.To confirm that the CLI has been installed, run the following command:
bash
blnk --version

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2. Install the Blnk TypeScript SDK

In your blnk project folder, install Blnk Typescript SDK.
bash
npm install @blnkfinance/blnk-typescript --save

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3. Create your first ledger

A ledger is a folder for grouping balances together in your Blnk server. To learn more, see the following: Introduction to Ledgers To create a ledger using the TypeScript SDK:
Create ledger
import { BlnkInit } from '@blnkfinance/blnk-typescript';

const blnk = await BlnkInit('<secret_key_if_set>', { baseUrl: 'http://localhost:5001' });
const { Ledgers } = blnk;

const newLedger = await Ledgers.create({
    name: "Customer Savings Account",
    meta_data: {
        project_owner: "YOUR_APP_NAME"
    }
});
console.log("Ledger Created:", newLedger);
You can confirm that the ledger has been created with the Blnk CLI:
bash
blnk ledgers list

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4. Create your first balance

A balance is used to represent a store of value in your Blnk server, e.g., wallet or account. To learn more, see the following: Introduction to Balances To create a balance using the TypeScript SDK:
Create balance
const { LedgerBalances } = blnk;

const newBalance = await LedgerBalances.create({
    ledger_id: "ldg_073f7ffe-9dfd-42ce-aa50-d1dca1788adc",
    currency: "USD",
    meta_data: {
        first_name: "Alice",
        last_name: "Hart",
        account_number: "1234567890"
    }
});
console.log("Balance Created:", newBalance);
You can confirm that the balance has been created with the Blnk CLI:
bash
blnk balances list

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5. Record your first transaction

Transaction records represent all financial activities (money in and money out) happening within your Blnk ledger. All transactions are immutable (cannot be modified or deleted) and idempotent (producing the same result no matter how many times an operation is performed). To record a transaction using the TypeScript SDK:
Create transaction
const { Transactions } = blnk;

const newTransaction = await Transactions.create({
    amount: 750,
    reference: "ref_001adcfgf",
    currency: "USD",
    precision: 100,
    source: "bln_28edb3e5-c168-4127-a1c4-16274e7a28d3",
    destination: "bln_ebcd230f-6265-4d4a-a4ca-45974c47f746",
    description: "Sent from app",
    meta_data: {
        sender_name: "John Doe",
        sender_account: "00000000000"
    }
});
console.log("Transaction Recorded:", newTransaction);
You can confirm that the transaction has been created with the Blnk CLI:
bash
blnk transactions list

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Need help?

We are very happy to help you make the most of Blnk, regardless of whether it is your first time or you are switching from another tool. To ask questions or discuss issues, please contact us or join our Discord community.

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Issue reporting

If you encounter any issues while installing or using this SDK, please report them on Github.