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 #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

    • Kaizen #152 - Client Script Support for the new Canvas Record Forms

      Hello everyone! Have you ever wanted to trigger actions on click of a canvas button, icon, or text mandatory forms in Create/Edit and Clone Pages? Have you ever wanted to control how elements behave on the new Canvas Record Forms? This can be achieved

    • Kaizen #142: How to Navigate to Another Page in Zoho CRM using Client Script

      Hello everyone! Welcome back to another exciting Kaizen post. In this post, let us see how you can you navigate to different Pages using Client Script. In this Kaizen post, Need to Navigate to different Pages Client Script ZDKs related to navigation A.

    • Recent Topics

    • Zobot operator information

      I am working on a zobot that calls a plug to send data to our API. I want the response data from that API to be shown only to the operator and not the customer. I have tried writing this data out to the visitorCity field but nothing gets updated on the

    • Copy paste from word document deletes random spaces

      Hello Dear Zoho Team, When copying from a word document into Notebook, often I face a problem of the program deleting random spaces between words, the document become terribly faulty, eventhough it is perfect in its original source document (and without

    • Is it possible to use module field filters via URL parameters?

      It would be really convenient if I could quickly link to a filter. For reference, this is the filter functionality I'm referring to: https://help.zoho.com/portal/en/kb/crm/customize-crm-account/advanced-filters/articles/advanced-filters For example: My

    • Transitioning FESCO Bill Project to Zoho Sheets and Integration Options

      Hello Zoho Support, I'm considering transitioning my FESCO bill project from Google Sheets to Zoho Sheets and wanted to know if there are integration options to seamlessly migrate our existing work. You can view our platform here, any guidance would be

    • Support for Custom Fonts in Zoho Recruit Career Site and Candidate Portal

      Dear Zoho Recruit Team, I hope you're doing well. We would like to request the ability to use custom fonts in the Zoho Recruit Career Site and Candidate Portal. Currently only the default fonts (Roboto, Lato, and Montserrat) are available. While these

    • Credit card

      Coming from another software, is it possible here to typically have credit card payment off, but independently per customer, click a box (possibly on the invoice when I go to to send) allowing that 1 allowed customer credit card payment, NOT ALL of my

    • Lightbox Pop-up form

      I would like to embed my form using the lightbox pop up. I don't want it to load automatically. I want it to load when some clicks the button. I can see this option, however when I use the "show pop-up launch button" on the website, the button automatically

    • Lightbox Pop-up form

      I would like to embed my form using the lightbox pop up. I don't want it to load automatically. I want it to load when some clicks the button. I can see this option, however when I use the "show pop-up launch button" on the website, the button automatically

    • Connecting Portals from different Zoho apps

      Hi, I note that Zoho has functionality for customer portals for several of the Zoho apps, like CRM, Projects, Desk etc. Is there any way to connect these portals?  It would be great if we could give our customers access to a portal in which they could

    • Customer Management: #5 Never Let the Customer Slip

      When Rahul started Knight's Watch Consulting, his focus was simple: deliver good work and keep clients happy. He offered one-time consulting projects, monthly advisory retainers and usage-based support for growing clients. Business was steady, and customers

    • Deluge date time issue

      The deluge function info zoho.currentdate.toString("MMM/YYYY") returns Dec 2026 instead of 2025

    • Zoho Projects Android and iOS app update: Mobile device permission based on user profiles

      Hello everyone! We have brought in support for mobile device permissions based on the user profiles which are configured in organization level. Administrators can now configure the permissions on the web app(projects.zoho.com) by following the steps mentioned

    • How do I add a blank line to the Organisation Address Format?

      I'd like to have my VAT number, for example, shown prominently by having a clear gap between it and the address block above, but any blank lines in the address format get ignored in PDF outputs.

    • treatment for rehires

            Hello,  we are aware of the fact that Zoho People at the moment does not has a provision for rejoining exited employees. But is there any quick fix or hack to this? It will be appreciated a lot. 

    • Zoho Projects Android and iOS app update: Timesheet module is now renamed as 'Time Logs', delete option has been renamed to 'Trash'.

      Hello everyone! We have now renamed the Timesheet module as Time Logs and the delete option as 'Trash' on the Zoho Projects Android and iOS app. Time Logs Android: Time Logs iOS: Trash option Android: Trash option iOS: Please update the app to the latest

    • Zoho Mail app update: Manage profile picture, Chinese (Traditional) language support

      Hello everyone! In the latest version (v3.1.9) of the Zoho Mail app update, we have brought in support to manage profile picture. You can now set/ modify the profile picture within the app. To add a new profile picture, please follow the below steps:

    • Reminders for Article Approval

      Is there a way to send reminders for approvers to review articles and approve/deny them? I'm not seeing that option anywhere.

    • Add Full-Screen Viewing for Quartz Recordings in the Client Interface

      Hi Zoho Team, We would like to request an enhancement to the Zoho Quartz client interface when viewing submitted recordings. Current Limitation: When viewing a Quartz recording from the client (user) interface, there is currently no option to switch the

    • 2025 Recap: A Year to Remember | Zoho Inventory

    • Important Update : Pipedrive deprecated fields no longer supported in Zoho Analytics

      Dear Pipedrive users, We would like to inform you about a recent update related to your Pipedrive integration with Zoho Analytics. The Pipedrive team has deprecated certain fields from their application. You can find more details in the official Pipedrive

    • Product Updates in Zoho Workplace applications | November 2025

      Hello Workplace Community, Let’s take a look at the new features and enhancements that went live across all Workplace applications this November. Zoho Mail Format comments easily using Slash Commands With Slash commands, you can easily format text, insert

    • Right-Click Pipeline to Open in New Tab

      Please add the ability to right-click on a pipeline to open it in a new tab

    • Adjusting Physical Inventory

      Not getting very far with support on this one, they say they are going to fix it but nothings happened since November. Please give this a thumbs up if you would like to see this feature or comment if you have some insight. Use Case: Inventory set to be

    • I need to Record Vatable amount and non vatable amount separately in zoho books in a single line

      I need to Record Vatable amount and non vatable amount separately in zoho books in a single line give me the customisation option and in invoice copy to customer the total amount should be inclusive 5%vat and no need to show the vatable and non vatable

    • Sending automated messages that appear in the ticket's conversation thread

      Good morning, esteemed Zoho Desk community, warm greetings Today I am here to raise the following problem, seeking a solution that I can implement: I need to implement an automation that allows me to send reminder messages to customers when I am waiting

    • sync views to sheet

      Im looking to sync my views aka reports in analytics to zoho sheets, when data is updated in analytics it also should be updated in sheets, till now zoho sheets only offer raw data connection and it is not enough as these reports are difficult to re-do

    • How to update the Status in a custom module?

      Hi, I have a custom module "cm_payment_registry" in Billing, I am trying to change the status which is "Draft" with: array = {"custom_status":"Approved"}; zoho.billing.update("cm_payment_registry",organization.get("organization_id"), XXXXXXXXXXXXXX, array,"connectionname");

    • Reporting Tags

      We've been using reporting tags for years (before itemizing was available) and now we are finding reporting these tags are impossible to track. Reports have changed in the customization and our columns of reporting tags no longer show up. We do not use

    • Opening balances - Accounts Receivable and Payable

      Our accounting year starts on 1st August 2013 and I have a Trial Balance as at that date, including Accounts Receivableand Accounts Payable balances, broken down by each customer and supplier. Q1 - do I show my opening balance date as 31st July 2013 or

    • Replace Zoho Invoice with QuickBooks

      We are implementing Zoho FSM for a cleaning business in the US with 50+ field workers. This business has been using Quickbooks for accounting for decades and will not migrate to Zoho Books. A major issue in the integration is the US sales tax calculation.

    • 2025 Highlights: A Year of Steady Progress and Significant Developments

      As we come to the end of 2025, let's take a moment to reflect on the significant progress and developments we've made to improve your travel and expense management. In the Spotlight Introducing Online Booking (US edition only - Early access) Enable online

    • Function #42: Show the actual rate of items on invoices

      Hello everyone, and welcome back to our series! In Zoho Books, you have the ability to create Price Lists, wherein you can mark up and mark down the item rates by a specific percentage or set custom rates. Generally, when you apply a price list to an

    • Ability to Set Text Direction for Individual Cells in Zoho Sheet

      Dear Zoho Sheet Team, We hope you are doing well. We would like to request an enhancement in Zoho Sheet that allows users to set the text direction (right-to-left or left-to-right) for individual cells, similar to what is available in Google Sheets. Use

    • New in CRM: Dynamic filters for lookup fields

      Last modified on Oct 28, 2024: This feature was initially available only through Early Access upon request. It is now available to all users across all data centers, except for the IN DC. Users in the IN DC can temporarily request access using this form

    • Warehouse fast processing

      Hey guys, would anyone be interested in something like the attached image ? If there's any interest I'd be willing to develop it further for others to use, it's much faster than using Zohos native solutions, it can part pack, pack in full, part ship,

    • Automatic Invoice Number generation for createRecord

      Hello, while testing some custom Buttons in my Zoho Books application, I noticed that I get an error that previously did not occur. After some further digging I found that the automatic transaction numbering of invoices no longer work in my organization.

    • Can I create a CODE 128 custom field for my items in Zoho Inventory and then use it for generating Sales Orders?

      Can anyone helps me, I don't want to use the SKU code for scanning my products.  ​Because all my products have a CODE-128 label attached.

    • Start/Stop Timmer in Chrome Extension

      The chrome extension is great and allows you to do allot however one of the most common things employees working on projects need to do is track their time. Having an easy start/stop timer to track time would be great.

    • Invalid collection string

      I haven't changed anything in one of my functions. I'm trying to run it manually and suddenly "Invalid collection string" appears. My code has 6 lines and the error says that the error is on 7th line. Why? What does this error mean? Nothing has been changed

    • Zoho Directory 2025: New Features | Security Enhancements | Enriched UI

      Hello everyone, Greetings from the Zoho Directory team! 2025 has been a highly successful year for Zoho Directory. We are delighted to introduce a fresh set of features, an enriched UI, and major product enhancements. These updates aim to deliver a smoother

    • Next Page