Persistent HTTP 403 Invalid checksum during Kite Connect authentication

sbabu29
Hello Zerodha Kite Connect Team,

I am facing a persistent authentication issue with my active Kite Connect app.

I have followed the official Kite Connect V3 authentication flow.

Details:

1. My Kite Connect app is active.
2. I successfully complete Zerodha login and authorization.
3. I generate a fresh request_token.
4. The request_token length is 32 characters.
5. I generated the SHA-256 checksum using:
api_key + request_token + api_secret
6. There are no leading or trailing spaces in the API key, API secret, or request token.
7. I am using the official Python KiteConnect package version 5.2.1.

I tested the authentication in two different ways.

TEST 1:
Official Python KiteConnect SDK

Result:
TokenException: Invalid `checksum`

TEST 2:
Direct POST request to:
https://api.kite.trade/session/token

Result:
HTTP 403
Zerodha message: Invalid `checksum`
Error type: TokenException

Therefore, both the official Python SDK and the direct API request are returning the same Invalid checksum error.

Could you please check whether there is any issue with my Kite Connect app/API-key configuration or authentication on the server side?

I can provide non-sensitive diagnostic details if required.

I am not posting my API secret, request token, or access token publicly.

Thank you.
Tagged:
  • sbabu29
    UPDATE:

    I have now created a completely new Active Kite Connect app specifically to isolate this issue.

    The new app was successfully created and authorized with a fresh Zerodha login and a fresh request_token.

    I then tested the new app using:

    1. Official KiteConnect Python SDK
    2. Independent direct HTTPS POST to /session/token
    3. Standalone diagnostic script

    Both tests return:

    HTTP 403
    Invalid checksum

    The local checks also confirm:
    - request_token length: 32
    - API key has no leading/trailing spaces
    - API secret has no leading/trailing spaces
    - request_token has no leading/trailing spaces
    - SHA-256 checksum length: 64

    The same problem therefore occurs with BOTH my old Connect app and a newly created Connect app.

    Could you please check from Zerodha's side whether there is any account-side, application-side, or backend issue affecting session-token generation for my account/apps?

    No API secret, request_token or access_token is being shared publicly.

    Thank you.
  • salim_chisty
    An Invalid checksum error generally indicates that the api_key, api_secret, or request_token being used is incorrect or does not correspond to the same authentication session. We have verified the Python SDK and found no issues.

    Please try generating the access token with a standalone login script rather than your application. This will help isolate whether the issue is related to the credentials or your application's authentication flow.

    We recommend following the login flow as outlined in the Kite Connect API documentation. Additionally, you can refer to this webinar for a detailed walkthrough. You can explore our QuantInsti course on Algorithmic trading with Zerodha Kite Connect API and Python.​
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