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

    • Can multiple agents be assigned to one ticket on purpose?

      Is it possible to assign one ticket to two or more agents at a time? I would like the option to have multiple people working on one ticket so that the same ticket is viewable for those agents on their list of pending tickets. Is something like this currently

    • Where is the settings option in zoho writer?

      hi, my zoho writer on windows has menu fonts too large. where do i find the settings to change this option? my screen resolution is correct and other apps/softwares in windows have no issues. regards

    • CRM gets location smart with the all new Map View: visualize records, locate records within any radius, and more

      Hello all, We've introduced a new way to work with location data in Zoho CRM: the Map View. Instead of scrolling through endless lists, your records now appear as pins on a map. Built on top of the all-new address field and powered by Mappls (MapMyIndia),

    • Zoho Sign Not Delivering

      I have sent several contracts out via Zoho Sign.   They do not seem to be getting delivered.  I had one person receive it, but the others have not.   I had one person tell me they sent it back to me and never got it and doesn't show as signed.  I've sent

    • Bank Feeds Breaking Constantly

      Hey Everyone, I have already reached out to support about this issue but I am wondering if anyone else is having the same issue. My bank feeds keep breaking within days of me fixing them by updating the credentials. Its been happening for a while and

    • Automatic Matching from Bank Statements / Feeds

      Is it possible to have transactions from a feed or bank statement automatically match when certain criteria are met? My use case, which is pretty broadly applicable, is e-commerce transactions for merchant services accounts (clearing accounts). In these

    • Zoho Payroll's USA and KSA editions are available in Zoho One!

      Greetings! We’re excited to share that Zoho Payroll, currently available only in India and the UAE, is now introducing the KSA (Kingdom of Saudi Arabia) edition and the USA (United States of America) edition, and these editions are now available in Zoho

    • Tip #63- Exploring Technician Console: Elevate to Admin Mode (Windows & Mac)- 'Insider Insights'

      Hello Zoho Assist Community! Ever been in a remote support session where you couldn’t complete a task because you didn’t have admin privileges? Maybe installing software, accessing secure system areas, or rebooting into Safe Mode just didn’t work because

    • Prevent accidental duplicate entry of Customer Ordersome

      Zoho Support has confirmed that Zoho currently does not have any method (using Deluge, flow or any other method) to alert a user when a sales order has been entered twice using the same customer reference number (i.e. a duplicate). Most ERP platforms

    • Zoho Mail - Email Reminder template (default)

      Zoho Mail Users, Does anybody here use the email reminder template? I'm asking Zoho to allow and add us to select which one of our many templates will be our default. It allows us to operate more efficiently. It's a Checkbox. If you feel this can benefit

    • Windows Desktop App - request to add minimization/startup options

      Support Team, Can you submit the following request to your development team? Here is what would be optimal in my opinion from UX perspective: 1) In the "Application Menu", add a menu item to Exit the app, as well as an alt-key shortcut for these menus

    • Canva Integration

      Hello! As many marketing departments are streamlining their teams, many have begun utilizing Canva for all design mockups and approvals prior to its integration into Marketing automation software. While Zoho Social has this integration already accomplished,

    • Announcement integration between Zoho People and Zoho Connect

      As we're using these 2 products, there're areas of overlapping especially in the Announcement. When there's a new announcement in Zoho People, can it push to the company wall in Zoho Connect?

    • Does Zoho Mail Have Popout windows?

      I recently switched my work email over to Zoho and everything I read said that you can popout the draft email as you're writing, however, all the pictures or info I've seen show the typical popout arrow in the top right, which I can not for the life of

    • Can I reorder how the staff are displayed on the booking page?

      As the title suggests, can I change this? Either reorder manually reoreded to my preference, or automatically (a-z, z-a etc.)

    • Bulk upload image option in Zoho Commerce

      I dont know if I am not looking into it properly but is there no option to bulk upload images along with the products? Like after you upload the products, I will have to upload images one by one again? Can someone help me out here? And what should I enter

    • Subheaders for Sections in forms

      Currently, every form section has a field name, which one can choose to show/hide to the end user. It would be great if there was an option to show a SUB-HEADER in addition to a header. It would be useful for explaining to the end user what the section

    • Custom view inconsistencies

      Why is "is not" missing from criteria, along with other comparison operators ??? It makes it almost impossible to build required custom views, I don't want "void" invoices listed & why on earth would "Void" invoices be showing when the criteria includes

    • Promote a layout to standard so I can delete one layout

      Similar to this and many other topics: https://help.zoho.com/portal/en/community/topic/set-layout-as-standard The problem, every model has a standard layout, which is what we use most of the time... But as the business grows and evolves we may have to

    • Can Zia summarize fields?

      A great use case of AI for me would be summarizing company descriptions. We often get long winded descriptions from databases or scraping websites, then reduce them to a couple of sentences stating what a company actually does. Is there any way within

    • Zoho Recruit Community Meet-up - India (Venues Finalised)

      Zoho Recruit Community Meet-up - India (Venues Finalised) Namaste, India. 🙏🏼 The Zoho Recruit team is hitting the road—and we're absolutely excited behind the scenes. Join us for the Zoho Recruit India Meet-up 2026, a morning designed to make your recruiting

    • [Webinar] Solving business challenges: Secure, real-time, and external collaboration

      Hi Zoho Writer users, We are excited to announce Zoho Writer's webinar for March 2026: Solving business challenges: Secure, real-time, and external collaboration. Zoho Writer supports real-time collaboration by allowing teams to work together in documents.

    • Table dimensions

      I try changing the dimensions of the table on my computer but it doesn't change. Do I have to be a premium member or does it only work on the app?

    • Zoho CRM Community Digest - January 2026 | Part 2

      Hello Everyone! Here’s the second part of January’s Zoho CRM Community Digest, rounding up the remaining highlights from the month. From newly rolled out updates to thoughtful implementation questions and practical solutions, the community once again

    • Find and Merge Duplicates to trigger webhook

      My sales team uses the Find and Merge Duplicates feature often to cleanup records in the CRM. We use webhooks to signal to our internal tools database when new Contacts are created, updated, or deleted, in order to keep our DB in sync with Zoho CRM. However,

    • Introducing WhatsApp integration and quick editing capabilities in Zoho Sign

      Hi there, Zoho Sign already helps users collect signatures via email and SMS, and we're happy to announce that you can now send documents and authenticate recipients right through WhatsApp. Some of the key benefits include: Communication with recipients

    • Dynamic Field Folders in OneDrive

      Hi, With the 2 options today we have either a Dynamic Parent Folder and lots of attachments all in that one folder with only the ability to set the file name (Which is also not incremented so if I upload 5 photos to one field they are all named the same

    • Logging Out of FSM

      I have tried to log out of FSM app of the last person and it will not let me do so. I need to log in to my account.

    • Enhancement in Zoho CRM: Control who gets to participate in a forecast by customizing the user hierarchy

      Include only users from the sales function; exclude the rest Dear Customers, We hope you're well! We started this year with a series of exciting enhancements to Zoho CRM and to this list, we are thrilled to add an enhancement to forecasting. Let's talk

    • Multiple Zoho One accounts

      Hello. I'm searching for a solution to run multiple organizations under 1 Zoho One account or have a different Zoho One account for each organization and still be able to easily login to each. Currently Zoho One doesn't allow the same email address to

    • Tips and tricks #63: Hold and Drag to select elements in the Show app for iOS

      Hello everyone! Welcome to another tips and tricks article. In today's article, we will learn about the Hold and Drag function in the Show app for iOS. The Hold and Drag option lets you select multiple elements on a slide quickly. Once they are selected,

    • Organize and manage PDFs with Zoho PDF Editor's dashboard

      Hello users, Zoho PDF Editor's dashboard is a one-stop place to upload, sort, share PDF files, and more. This article will explore the various capabilities that Zoho PDF Editor's dashboard offers. A few highlights of Zoho PDF Editor's dashboard: Upload

    • Possible to generate/download Quote PDF using REST API?

      See title. Is there any way after a quote has been created to export to a PDF using a specified template and then download it? Seems like something that should be doable. Is this not supported in the API v2.0?

    • Free Webinar - AI for email: Helpful or Hype?

      Hello, Zoho Mail community! 👋 We're kicking things off with a webinar you won't want to miss—and yes, we're going there: Is AI in email actually useful, or is it all hype? In this session, two of our experts will have an open, no-fluff conversation about

    • Balancing access, security, and productivity with Email Policy

      An organization typically includes multiple user groups, such as leadership, sales, and support, each with different email usage patterns and security needs. Administrators must balance flexibility and control, thereby ensuring email usage aligns with

    • Is it possible to update multiple work items at once?

      Hi, Is it possible to update the statuses/release tags of multiple work items at once? I came across this thread that says it's not possible at the moment, but it was related to the Sprints mobile app. Does this feature not exist in the website as well?

    • See Every IM Conversation as It Happens

      Instant messaging moves fast. Customers expect quick replies and smooth conversations across WhatsApp, Instagram, Facebook, and live chat. But without real-time visibility, small issues become big problems. A session stays open longer than expected. A

    • Release Notes | January 2026

      We have rolled out a set of powerful new enhancements across Zoho Vertical Studio that bring several long-awaited capabilities to your applications. These updates focus on deeper customization, smarter automation, better reporting, and improved usability

    • Product Request: Send email to Secondary email

      Guys, we should be able to send the campaign to the secondary email too.  Is this on the plans for Zoho Campaign? It looks like I can map the secondary email from the CRM to the Campaigs, but can not send the message.  

    • Franchise

      Is there a solution of how to organize global franchise organisations?

    • Next Page