Kaizen #191: Implementing "Login with Zoho" using Python SDK

Kaizen #191: Implementing "Login with Zoho" using Python SDK

      
Welcome back to another week of Kaizen!!

This week, we are diving into how to implement secure user authentication using Login with Zoho and integrate it with Zoho CRM through our Python SDK.

To ground this in a real-world scenario, we will look at how Zylker Academy, a training institute offering web design and development courses, uses an internal portal that connects directly to Zoho CRM. This setup allows course coordinators to manage student data without maintaining a separate backend database.

Zylker receives frequent student enquiries and uses Zoho CRM to manage all related information. Every course coordinator, academic advisor, and support staff member who needs access to student information is added as a user in Zoho CRM, with access permissions aligned to their role. Instead of using Zoho’s interface directly, Zylker’s team works through a custom internal web portal, tailored to their workflow. This portal connects directly to Zoho CRM, reading from and writing to it, but does not have its own database.

But before this portal can access any CRM data, it must authenticate itself securely. Every time a user opens the portal, they must log in with their Zoho account. Once authenticated, they will be granted access to the CRM modules and records they are authorized to work with. That is where Login with Zoho comes in.

What is "Login with Zoho"?

Login with Zoho is Zoho’s implementation of the OAuth 2.0 Authorization Code flow. It allows applications to authenticate users and access their Zoho CRM data without ever handling their passwords.
Instead of asking users for their Zoho credentials directly, the app redirects them to Zoho’s login screen. Here is how it works:
  1. The app redirects the user to Zoho’s login page.
  2. The user logs in and approves the requested permissions (scopes).
  3. Zoho sends back an authorization code.
  4. The backend exchanges this code for access and refresh tokens.
  5. These tokens are used to make authenticated API calls.
This flow ensures that users maintain full control over their data. They can revoke access at any time, and your application never handles or stores passwords. 
In Zylker’s case, every time a coordinator opens the portal, they are prompted to log in with their Zoho account. Once authenticated, they can immediately begin working with student records—all backed by Zoho CRM.

Use Case Implementation: Zylker’s Student Management Portal

To demonstrate how this login flow works, we have built a stripped-down version of Zylker's portal:
  • A front-end form to enter and view student data
  • A backend server that interacts with Zoho CRM via the Zoho CRM Python SDK
The application includes a simple form for capturing student details—name, college, course, email, and phone number. Submitted data is treated as a Lead in Zoho CRM.
The app allows users to:
  • Add new leads
  • View a list of all registered leads
  • Edit an existing lead’s information
  • Delete records if necessary
All actions go straight to Zoho CRM using its Python SDK. But before any of this can happen, the user must complete the login flow.

Sample Project Structure

Before going into the implementation details, let us briefly define the components of the project.

Frontend
The frontend is a simple static web interface built with HTML, CSS, and JavaScript. It runs in the browser and handles user interactions and triggers backend API calls. These are the main files:
  • index.html : Main UI for login, data entry, and record viewing.
  • script.js : Contains the client-side logic to trigger login, submit data, and render records.
  • redirect.html :  A minimal page used to capture the authorization code returned by Zoho after login.
The frontend is served using any static server (e.g., Live Server in VS Code) and runs on http://localhost:5501/ in our example. 
Download the files from here.
Configuration Notes:
  • In script.js, update the redirect_url value in the login request to match your actual domain or port if you’re not using localhost:5501.
  • Ensure the URL in the Zoho API Console matches this redirect URI and port.
Backend
The backend is a Python server that handles all interactions with Zoho CRM via the Python SDK. It includes:
  • server.py : A custom HTTP server that:
    • Generates the Zoho login URL
    • Exchanges the authorization code for tokens
    • Initializes the SDK
    • Exposes endpoints like /create, /get_records, /update, and /delete
  • record.py : Contains functions to create, fetch, update, and delete records in CRM modules like Leads. Each function uses the Zoho Python SDK methods to perform a specific operation.
This server runs on http://127.0.0.1:8085/ in our example. 

Download the files from here.
Configuration Notes:
  • In server.py, replace the client_id with your actual client ID from Zoho's API Console.
  • In record.py, replace the client_secret with your actual client secret.
  • If required, change the front-end server’s host and port in the run() function at the bottom of server.py:
    def run(server_class=HTTPServer, handler_class=SDKInitialize, port=xxxx):

Sample project flow

      

Step 1: Register the application with Zoho API console

To initiate the login process, you need to register your application on the Zoho API Console. This is a one-time setup that provides your app with a Client ID and Client Secret, both of which are required to authenticate users and exchange authorization codes for tokens.
To register your application:
We will be using these values in the backend script (server.py)  that handles token exchange.

NotesNOTE: To support users from multiple data centres, make sure to enable multi-DC support for your application. You can do this by going to your app’s settings in the Zoho API Console and turning on the Multi-DC option.

Step 2: Implementing the login flow

Here is a walkthrough of the flow implemented in the project:

1. Page loads and triggers login

When a user opens the portal, the frontend automatically initiates the login sequence. It first makes a call to the backend to retrieve the Zoho authorization URL. 

In index.html, this triggers getRecords() on page load:
  1. <body onload="getRecords();">
In script.js, getRecords() calls the login() function:
  1. async function getRecords() {
  2.     login();
  3. }
The login() function sends a request to the backend to get the Zoho OAuth authorization URL.

2. Backend builds login URL

The backend responds with an OAuth URL that includes:
  • Your client ID
  • Scopes like ZohoCRM.modules.ALL
  • The redirect URI
In server.py, under do_GET, the /login endpoint generates the OAuth URL:
  1.    if parsed_url.path == '/login':
  2.             redirect_url = query_params.get('redirect_url', [''])[0]
  3.             scope = "ZohoCRM.settings.fields.ALL,ZohoCRM.modules.ALL,ZohoCRM.users.READ,ZohoCRM.org.READ"
  4.             url = "https://accounts.zoho.com/oauth/v2/auth?scope=" + scope + "&client_id=" + self.client_id + \
  5.                   "&redirect_uri=" + redirect_url + "&response_type=code&access_type=offline"
  6.             self._set_headers()
  7.             # Send response
  8.             response = {"url": url, "redirect_url": redirect_url}
  9.  self.wfile.write(json.dumps(response).encode('utf-8'))
Once the frontend (script.js) receives the login URL, it opens it in a popup window.
  1. const response = await fetch('http://127.0.0.1:8085/login?redirect_url=http://127.0.0.1:5501/redirect.html');
  2. const data = await response.json();
  3. const popup = openCenteredPopup(data.url, "PopupWindow", 600, 400);
Here's an example of the Zoho OAuth authorization URL format:
      scope=ZohoCRM.modules.ALL&
      client_id=YOUR_CLIENT_ID&
      response_type=code&
      access_type=offline&
      redirect_uri=YOUR_REDIRECT_URI

3. User logs in on Zoho

The user logs in with their Zoho credentials and is prompted to approve the app's access. Once they approve, Zoho redirects them to the specified redirect URI along with an authorization code and location parameter. The location parameter indicates which data centre the user belongs to.

4. Frontend captures the authorization code

The redirect page, a minimal HTML file (redirect.html),  reads the URL parameters and stores them in localStorage, then closes the popup:
  1. function setAccessToken() {
  2.     var hashProps = getPropertiesFromURL();
  3.     if (hashProps) {
  4.         for (var key in hashProps) {
  5.             if (hashProps.hasOwnProperty(key)) {
  6.                 localStorage.setItem(key, hashProps[key]);
  7.             }
  8.         }
  9.     }
  10.     setTimeout(function () { window.close(); }, 0);
  11. }

5. Token exchange and SDK initialization

Once the popup window is closed, the main window retrieves the authorization code and location and sends them to the backend’s /initialize endpoint.
In script.js:
  1. var code = localStorage.getItem("code");
  2. var location = localStorage.getItem("location");
  3. initialize(code, location, data.redirect_url);
  4. .
  5. .
  6. async function initialize(code, location, redirect_url) {
  7.     const response = await fetch('http://127.0.0.1:8085/initialize?code=' + code + '&location=' + location + '&redirect_url=' + redirect_url);
  8. }
In server.py, the /initialize endpoint handles SDK initialization:
  1. elif parsed_url.path == '/initialize':
  2.     code = query_params.get('code', [''])[0]
  3.     location = query_params.get('location', [''])[0]
  4.     redirect_url = query_params.get('redirect_url', [''])[0]
  5.     LeadsRecords().init(self.client_id, code, location, redirect_url)
In record.py, the SDK is initialized and tokens are stored.
  1. token = OAuthToken(client_id=client_id,
  2.                    client_secret=client_secret,
  3.                    grant_token=code,
  4.                    redirect_url=redirect_url)
  5. Initializer.initialize(environment=environment,
  6.                        token=token,
  7.                        logger=logger,
  8.                        store=store)  # FilePersistence or custom store
This exchanges the authorization code for:
  • An access token (valid for one hour)
  • A refresh token (used to get new access tokens)
These tokens are saved in a local file (sdk_tokens.json). This is configured using Zoho’s FilePersistence class during SDK initialization 

How are tokens linked to users?

The SDK maps each access and refresh token pair to a unique user-organization combination. This means tokens generated for different organizations by the same user are stored separately. Likewise, if a user generates new tokens for the same organization, the SDK updates the existing tokens instead of creating duplicates. This ensures that API calls always use the correct tokens tied to the authenticated user and their organization. 

To enable this mapping, the SDK retrieves the user and organization information in the background. This requires the appropriate scopes to be included during authentication, ZohoCRM.users.READ and ZohoCRM.org.READ. Without these scopes, the SDK cannot identify the user-org combination correctly, which can lead to multiple token entries for the same user. That is why, in our sample project, we have included these scopes explicitly in the server.py file during the SDK initialization.

Once the SDK is initialized, the user is logged in, and the app can begin making CRM API calls on their behalf.


Step 3: Accessing Zoho CRM

Once the user is authenticated and the Zoho SDK is initialized on the backend, the frontend can call custom backend endpoints like /create or /get_records. These endpoints use the authenticated SDK instance to make CRM API calls on behalf of the user.
  • GET /get_records?module=Leads : View all students
  • POST /create?module=Leads : Add new student
  • PUT /update?module=Leads&id=... : Edit existing entry
  • DELETE /delete?module=Leads&id=... : Remove existing entry

Deploying the sample project

To run this application, you will need two components:
  1. A frontend server to serve your HTML files (index.html, script.js, redirect.html). This can be done using any static web server (e.g., Live Server in VS Code).
  2. A Python backend server that handles login, token storage, and CRM API communication. You can run it using:
    python server.py
In the given example, both servers communicate over localhost. You should set your redirect URI accordingly when registering your app in the Zoho console.

Conclusion

Login with Zoho is a secure, OAuth-based mechanism that allows users to authorize your application to access their Zoho CRM data. In this example, we built a real-world use case, a student portal for Zylker Academy, that authenticates users and interacts with CRM directly using the Zoho CRM Python SDK.
By walking through the entire flow, you now understand:
  • Why OAuth is essential for secure CRM access
  • How to register an application in Zoho
  • What the login and token exchange flow looks like
  • How to implement "Login with Zoho" in your applications

What is next?

In this project, we have used a simple file persistence method to store the token files. But in a real world scenario, this may not always meet your business requirements. In next week's Kaizen, we will implement custom token persistence instead of file persistence in the current project. We will explain how to implement this using SQLite, In-Memory and List DBs. With that, you will be equipped to implement a persistence method that fits your application architecture and deployment environment.

We hope that you found this useful. If you have any queries, let us know the comments below, or send an email to support@zohocrm.com. As always, we would love to hear from you!!

Stay tuned for next week's Kaizen : Implementing Custom Token Persistence 


Download Links:
Further Reading:

    • Sticky Posts

    • Kaizen #198: Using Client Script for Custom Validation in Blueprint

      Nearing 200th Kaizen Post – 1 More to the Big Two-Oh-Oh! Do you have any questions, suggestions, or topics you would like us to cover in future posts? Your insights and suggestions help us shape future content and make this series better for everyone.

    • Kaizen #226: Using ZRC in Client Script

      Hello everyone! Welcome to another week of Kaizen. In today's post, lets see what is ZRC (Zoho Request Client) and how we can use ZRC methods in Client Script to get inputs from a Salesperson and update the Lead status with a single button click. In this

    • Kaizen #222 - Client Script Support for Notes Related List

      Hello everyone! Welcome to another week of Kaizen. The final Kaizen post of the year 2025 is here! With the new Client Script support for the Notes Related List, you can validate, enrich, and manage notes across modules. In this post, we’ll explore how

    • Kaizen #217 - Actions APIs : Tasks

      Welcome to another week of Kaizen! In last week's post we discussed Email Notifications APIs which act as the link between your Workflow automations and you. We have discussed how Zylker Cloud Services uses Email Notifications API in their custom dashboard.

    • Kaizen #216 - Actions APIs : Email Notifications

      Welcome to another week of Kaizen! For the last three weeks, we have been discussing Zylker's workflows. We successfully updated a dormant workflow, built a new one from the ground up and more. But our work is not finished—these automated processes are

      • Recent Topics

      • Building Toppings #2 - Learn how to use Bigin's Developer Console to build toppings

        Hey Biginners, In our last post, we discussed what toppings are, why they're essential to extending Bigin's capabilities, and how the Bigin Developer Center serves as the starting point for building them. As a cloud platform, the Developer Center empowers

      • Links are incorrect when sent out

        I'm adding in hyperlinks into my eDM. When I send a test email, it's all correct. However, when I send out the eDM, all the hyperlinks jump up one space so none of the links are opening to the correct page. Why is this happening and how can I fix it?

      • Tip of the week #16 - Search and filter threads based on criteria

        Zoho TeamInbox lets you search and filter threads with any information that you have about the thread. You just have to input the criteria and Zoho TeamInbox will list all the threads that match the condition.   Firstly, there is a global search you can

      • Introducing recipient authentication via Stripe Identity in Zoho Sign

        Hi everyone! It's important to authenticate your recipient's identity before they access and sign important documents to ensure the highest level of compliance. Zoho Sign already helps businesses do this with various authentication methods: SMS OTP Email

      • Keep Converted Leads

        How do I keep the converted leads in the Leads Module after conversion (converting it to account, contact, deal). I want to add it in a converted stage in the leads module in order to get a report or dashboard and see all converted leads from my pip

      • Customizing Global Search Settings for All Users

        Hi Our team use the brilliant global search functionality within CRM many many times daily. But, we struggle with the out-of-the box columns that CRM gives you. We are always telling users to customize this look to more suit our business, to show the

      • Introducing Formula Fields for performing dynamic calculations

        Greetings, With the Formula Field, you can generate numerical calculations using provided functions and available fields, enabling you to derive dynamic data. You can utilize mathematical formulas to populate results based on the provided inputs. This

      • Tip of the Week #77– Stay informed of the activities happening in your organization

        Whenever a message is handled in Zoho TeamInbox, every action is recorded in the Activity Log. This ensures you always know what’s happening across your teams and inboxes. To access it, simply click the Audits icon on the left pane’s top bar after logging

      • Zoho Logs - Not seeing logs since 30 Nov

        Hi, we have a few functions running, I am testing some new ones and noticed that although I can see executions, I cannot see any logs, even when the first line on the functions is a log. I reviewed some existing functions, one of which is invoked on a

      • Workdrive MS Office integration

        Have installed subscribed version of Zoho WorkDrive VSTO runtime not found is the error when I try to install Zoho_WorkDrive_For_Office Unable to open work files in Excel and Word Urgent, since I have migrated all my OneDrive files to work drive already

      • How to change Zoho Vault password

        I am searching where I can change the Vault Password after having changed the Zoho account password. I don't see this option anywhere in my account. It should be simple and accessible! Please help. Thanks!

      • Zoho Workdrive - Communication / Chat Bar

        Hi Team, Please consider adding an option to allow admins to turn on or off the Zoho Communication Bar. Example of what I mean by Communication Bar: It's such a pain sometimes when I'm in WorkDrive and I want to share a link to a file with a colleague

      • When Marking a Multiple Choice Answer Exclusive - Not Following My Survey Disqualification Logic

        Using a multiple choice (many answers) question and I created survey disqualification logic that was working as intended. My question: Disqualification page logic is: If (QUESTION) is "any one of the following" then (OPTIONS) - a custom message populates

      • Where to Add Machines as Products to Map with Assets in Zoho FSM?

        implementing Zoho FSM for a clinical equipment supply company. The business sells and installs clinical machines in hospitals and clinics, and they also handle service requests, scheduled maintenance, calibration visits, and general machine upkeep. In

      • Show Zoom Link in Recipient's Calendar

        We set up meetings within a record, selecting the "Make this an online meeting".  We use Zoom. Most of the recipients go to their calendar (usually Gmail or Outlook, corporate) to join the Zoom meeting, but there is no Zoom link in the calendar. Can this

      • Zoho Bigin - should be able to link a "contact" to multiple "companies"

        Hello Support, I called into telephone support and was told that a contact can only be linked to one company. We have situations were director are contacts of and directors of multiple companies so that seems a basic weakness in Bigin. When go to add

      • Does Thrive work with Zoho Billing (Subscriptions)?

        I would like to use Thrive with Zoho Billing Subscriptions but don't see a way to do so. Can someone point me in the right direction? Thank you

      • Radio button data won't update

        Wondering if anyone is experiencing the same problem. I tried bulk updating our data on Zoho Creator using API and noticed that the radio button field wasn't updated. I have tried updating it manually, it didn't work. When I tried updating a text field

      • Introducing Global Sets for easy management of similar picklists in CRM

        Latest update (December 2025): You can now apply color coding to the values inside a global set, the same way you color code values in regular picklist fields. Update (Sep 2024): We've increased the maximum count limit for global sets. These new limits

      • No Ability to Rename Record Template PDFs in SendMail Task

        As highlighted previously in this post, we still have to deal with the limitation of not being able to rename a record template when sent as a PDF using the SendMail Task. This creates unnecessary complexity for what should be a simple operation, and

      • New in CPQ: Smarter suggestions for Product Configurator by Zia, and additional criteria in Price Rules

        Hello everyone! CPQ's Product Configurator in Zoho CRM allows sales teams to define structured product bundles through configuration rules, ensuring that the right product combinations are applied consistently in quotes. Admins set up these configurations

      • Process between CRM and Campaigns to ensure double opt-in contacts?

        I would like to ask for a few clarifications to ensure we fully comply with best practices and legal requirements: According to the documentation (Zoho Campaigns CRM sync – Default option), the best and recommended way to sync contacts is by using the

      • Zoho Books - New Interface keep details with PDF View

        Hello, The Zoho Books Interface has changed for estimates etc... One thing is causing issues though. Before the change, in PDF view you could see the detail information including custom fields entered for the estimate. Now, you have to switch between

      • Tip #52- Zoho Assist Downloads: Everything You Need in One Place- 'Insider Insights'

        Looking to start remote support sessions faster, manage unattended devices effortlessly, or join sessions without any hassle? The Zoho Assist Downloads Center has all the tools you need—across desktop, mobile, IoT, and browser environments. With our range

      • Condition based aggregate fields in subforms

        Hello everyone, We're excited to inform you about the latest enhancements made to our aggregate field capabilities in subforms; create aggregate fields based on conditions! An aggregate field is a column on which a mathematical function has been applied.

      • SalesInbox

        Sorry for saying this but SalesInbox is a really mess. BIG FAIL. Bad UX and VERY bad IMAP sync. I don't know how can someone use this to be more productive. It's just the oposite. I'm trying to use SalesInbox for a while but sales people do not have just sales activities so we still have to came back to the mail app anyway. Folders of SalesInbox are not in sync with folders of mail server (wich syncs Ok to mobile) and vice-versa wich leads to double work as now you have to cleanup 3 inboxes (Mail

      • Print labels on selected view

        How can I print labels for select view. Always defaults to ALL contacts when I select View = Mailing Labels. Thanks!!

      • Update CRM Price Books to include volume discounts as per Zoho Books/Inventory

        Once again, Zoho has 3 great products that all store information in different ways (which is not helpful when you attempt to integrate the 3 products - one of the best features of Zoho). Zoho CRM Price Books are basic at best. Zoho Books/Inventory Price

      • Tip #40- Strengthen Remote Support with IP-based Restrictions in Zoho Assist– ‘Insider Insights’

        Protecting sensitive data and preventing unauthorized access is a top priority for any organization. With IP-based restrictions in Zoho Assist, you can ensure that only users from trusted networks can initiate remote support sessions. Say your IT team

      • Printing Client Lists

        I was looking for a way to print out client lists based on the account. For example if I want all my contacts from company A on one sheet, how would I do this. Moderation Update (3rd December 2025): There are two challenges discussed in this thread. 1.

      • Qwen to be the default open source Generative AI model in Zoho Desk

        Hello everyone, At Zoho Desk, we will make the latest Qwen (30B parameters) the default LLM for our Generative AI features, including Answer Bot, Reply Assistant, and others. As a subsequent step, we will discontinue support for Llama (8B parameters).

      • ZOHO Blueprint and Workflow

        Hi, Correct me if i'm wrong, Blueprint triggers when a record that meets the criteria is created. It follows a specific transition that you will be setting up. Does blueprint work if the first state was triggered by a workflow? For example, In my custom module 1, I have a field named status. The statuses are 1, 2, 3 and 4. As soon as I create a new record, a workflow triggers that updates the status field to 1. Can a blueprint start from 2? My other concern is, can blueprint transitions work at the

      • Zoho CRM Participants Automatic - Invite Using Deluge

        Hi Zoho! Is there a way to make the invitations automatic via API? I'm using this one but it doesn't work or reflect in the CRM: participantUser = Map(); participantUser.put("type","email"); participantUser.put("participant",email); participantUser.put("invited",

      • Greek character in Deluxe script

        Hi, We have been using a script since 2022 which replaces characters in Greek contact names using replaceAll. Since this morning, all the Greek characters used in the script have turned to question marks. I tried retyping the characters, copy-pasting

      • Work Order Assignment for Engineers Handling Their Own Requests

        I’m setting up FSM for a business where there are multiple engineers, but each engineer handles their own process end-to-end receiving the service request, creating the work order, and completing the field service job. I noticed that I must create an

      • Experience Zoho Show on Mac now!

        Work today isn’t tied to a single place, time, or routine. It happens in cafes between meetings, on flights, or late at night when ideas strike. And when ins, your tools need to be ready, wherever you are. That’s why we built the Zoho Show app for Mac.

      • 【開催報告】東京 ユーザー交流会 Vol.4 | Zoho CRM 自動化のコツ ・Bookings のビジネス活用シーンとおすすめ機能を紹介

        ユーザーの皆さま、こんにちは。コミュニティチームの藤澤です。 11月28日(金)に新橋で「東京 ユーザー交流会 Vol.4」を開催しました。ご参加くださったユーザーの皆さま、ありがとうございました。ユーザー交流会の年内開催は、今回が最後でした。 この投稿では、当日のセッションの様子や使用した資料を紹介しています。残念ながら当日お越しいただけなかった方も、ぜひチェックしてみてください😊 ユーザー活用事例セッション：関数やクライアントスクリプトまで、CRMをもっと便利に Zoho CRM には、ワークフローやブループリントなど、さまざまな自動化に役立つ標準機能が備わっています。さらに、関数（Deluge）のようにスクリプトを記述して高度な自動化を実現することもできます。

      • Kiosk Button Actions

        I need to add an action to a Kiosk Button to loop me back to start the kiosk again and I am not sure what that looks like (function, etc.).

      • Dependent drop-downs... how?

        Good day. I have 2 different situations where I need a dependent drop-down field. First is for a subform, where I want to show related fields for a specific customer on the main form. In my case it is a parent whose children make use of our school transport

      • Reporting Limitation on Lead–Product Relation in Zoho CRM

        I noticed that Zoho CRM has a default Products related list under Leads. However, when I try to create a report for Lead–Product association, I’m facing some limitations. To fix this, I’m considering adding a multi-lookup field along with a custom related

      • Next Page