Using the SDK

Configurable client options ship in v1.3.0. See the Changelog before upgrading.

Initialize the client

Your Blnk client is the single entry point to everything: ledgers, balances, transactions, webhooks, and more. Configure it once when your app starts, then use it everywhere.

blnk_client.py

import os

from blnk_sdk import BlnkClientOptions, blnk_init

api_key = os.environ.get("BLNK_API_KEY", "")
base_url = os.environ.get(
    "BLNK_BASE_URL",
    "http://localhost:5001",
)

blnk = blnk_init(
    api_key,
    BlnkClientOptions(base_url=base_url),
)

That’s it. One import, one call, one client. From here you can create ledgers, move money, reconcile transactions, and manage your entire financial infrastructure.

create_ledger.py

from blnk_client import blnk

response = blnk.ledgers.create(
    {
        "name": "Customer Savings Account",
        "meta_data": {
            "project_owner": "YOUR_APP_NAME",
        },
    }
)

print("Ledger Created:", response.data)

Use a context manager when you want the underlying requests.Session closed automatically:

from blnk_sdk import BlnkClientOptions, blnk_init

with blnk_init(api_key, BlnkClientOptions(base_url=base_url)) as blnk:
    response = blnk.ledgers.create({"name": "Temporary ledger"})

Authentication

blnk_init takes two arguments: an API key and a BlnkClientOptions object. The options object must include base_url, the root URL of your Blnk Core instance. The SDK sends the API key on every request in the X-Blnk-Key header. How you set the API key depends on whether Core runs in secure mode:

Secure mode
Auth disabled

When server.secure is enabled, pass your API key as the first argument. Set base_url to the URL where Core is reachable.

import os
import { RelatedTopics } from "/snippets/related-topics.jsx";

from blnk_sdk import BlnkClientOptions, blnk_init

api_key = os.environ.get("BLNK_API_KEY", "")
base_url = os.environ.get(
    "BLNK_BASE_URL",
    "http://localhost:5001",
)

blnk = blnk_init(
    api_key,
    BlnkClientOptions(base_url=base_url),
)

When secure mode is off, pass an empty string as the first argument.

from blnk_sdk import BlnkClientOptions, blnk_init

blnk = blnk_init(
    "",
    BlnkClientOptions(base_url="http://localhost:5001"),
)

Secure Blnk

Secure mode, master key, and server hardening.

Scoped API keys

Owner-scoped keys and permission limits.

Timeouts and retries

When connections fail, Core restarts, or requests hang, the SDK handles it without blocking your app. Pass these parameters on BlnkClientOptions:

from blnk_sdk import BlnkClientOptions, blnk_init

blnk = blnk_init(
    api_key,
    BlnkClientOptions(
        base_url="http://localhost:5001",
        timeout=30000,
        retry_count=3,
        retry_delay_ms=2000,
    ),
)

Option	Type	Default	What it does for you
`timeout`	`int`	`10000`	Milliseconds to wait before giving up on a request. Bump this for slow operations like bulk reconciliations.
`retry_count`	`int`	`1`	Total attempts including the first. `1` means one attempt, no retries. `3` means try up to 3 times.
`retry_delay_ms`	`int`	`2000`	Milliseconds between retries. Uses linear backoff.

When to tune these:

Keep defaults if you’re making fast, local calls and want to fail fast.
Increase timeout if you’re running large batch requests that may take a while to complete synchronously.
Increase retry_count if you’re reading data across an unreliable network.

Custom logger

By default, the SDK logs internal events through a built-in logger that writes to the console with INFO:, ERROR:, and DEBUG: prefixes. Pass a custom logger to route these messages to your own logging system instead of the console.

from blnk_sdk import BlnkClientOptions, CustomLogger, blnk_init


class AppLogger(CustomLogger):
    def info(self, message, *meta):
        app_logger.info(message, extra={"meta": meta})

    def error(self, message, *meta):
        app_logger.error(message, extra={"meta": meta})


blnk = blnk_init(
    api_key,
    BlnkClientOptions(
        base_url="http://localhost:5001",
        logger=AppLogger(),
    ),
)

Metadata passed to the logger is redacted. The SDK strips values for keys such as api_key, authorization, token, and secret before logging.

Level	When the SDK calls it
`info`	Before a retry, or when a retryable `GET` failure will be retried
`error`	When a request times out, returns a non-retryable HTTP error, or fails with a network error

Example logs

INFO: Retrying request to transactions/txn_f482a1b3-6c2d-4e89-a17b-3d5e8f2a1c94 { attempt: 2, maxAttempts: 3, delayMs: 2000 }

ERROR: Request timed out { endpoint: 'transactions/txn_f482a1b3-6c2d-4e89-a17b-3d5e8f2a1c94', timeoutMs: 30000 }

ERROR: Request to transactions/txn_f482a1b3-6c2d-4e89-a17b-3d5e8f2a1c94 failed with status 404.

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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Ledgers

Ledger balances

Transactions

Reconciliation

Identities

Metadata

Hooks

Search

API keys

System

Initialize the client

Authentication

Secure Blnk

Scoped API keys

Timeouts and retries

Custom logger

Need help?

​Initialize the client

​Authentication

Secure Blnk

Scoped API keys

​Timeouts and retries

​Custom logger

​Need help?

Initialize the client

Authentication

Timeouts and retries

Custom logger

Need help?