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

        • Automate pushing Zoho CRM backups into Zoho WorkDrive

          Through our Zoho One subscription we have both Zoho CRM and Zoho WorkDrive. We have regular backups setup in Zoho CRM. Once the backup is created, we are notified. Since we want to keep these backups for more than 7 days, we manually download them. They

        • Boost your CRM accuracy with smart Data Enrichment

          Hello all! In this post let's look at data enrichment from a holistic perspective to gain more clarity on how you can use it. So, here's a quick recap of what data enrichment is and how you set it up it to enhance your existing module data! What is data

        • Is it possible to set a region lookup table so that my deal country can lookup this lookup table

          Hi there, I would like to be able to add a data lookup table with the following fields: Country, Region. And then in my deal report, i can then lookup this table to fish out the region in my report. This will be important for my sales process to categorise

        • Test Emails Show Sent "via zcsend.net" in My Gmail Account

          I noticed the following info... However, a few email service providers such as Outlook and Gmail will display that the email was sent by zcsend.net (Zoho campaigns’ server) on your behalf instead of just your from email address.  In order to prevent this, you can go for either of these options: Do not select the check box meant for DomainKey Signature which is listed under Unverified sender domains. Include our mail servers by advanced authentication method such as SPF/ Sender ID and DomainKey/ DKIM.

        • 'UnAuthenticated Connection: zbooks_connection'

          I have a zoho connection in Zoho Books, the link name es zbooks_connection, but I like to validate if exist, by example if I use this line in my code: response=zoho.books.getTemplates("", "","zbooks_connection"); But I don't  have the connection I like

        • Calling the new 'Custom API' feature from within a Custom Widget

          From what I've learned it is not possible to call an endpoint from the new "Custom API" feature within a Creator Widget. The SDK's doesn't support it yet, when calling it natively you end up with CORS issues or at least I couldn't get it working even

        • Cannot post to Instagram. I get the error: Insufficient permission to publish on this page. Check with your page Admin to update permissions.

          We had another admin that left the company. Since he left, we get this error when posting to Instagram.

        • Zoho desk desktop application

          does zoho desk has a destop applicaion?

        • Ability to re-order Workflow Rules

          We really need the ability to re-order workflow rules within departments.  Either the ability to drag/drop them into a different order or something.

        • Ticket to article and Ticket to template

          Hello! I would like to know if it is possible (and how) to do the following actions: 1. To generate an article from a ticket (reply + original message) 2. Easy convert an answer to an email template

        • Create an article template

          I have a question concern the Knolwedge Database from Zoho Desk. There is any possibility to create an article template ? Exemple of what I research : TODAY : I want to create a lot af articles with the same baseline > I create one article > I copy/paste

        • Persisting email signals to contact timeline?

          Hello there. Regarding the email signals that are logged when a contact opens an email, am I correct that these signals are not logged to a contact's timeline? Ideally, I would like to have this context available for future follow-ups, if the contact

        • Change of Blog Author

          Hi, I am creating the blog post on behalf of my colleague. When I publish the post, it is showing my name as author of the post which is not intended and needs to be changed to my colleague's name. How can I change the name of the author in the blogs?? Thanks, Ramanan

        • Zoho FSM API Delete Record

          Hi FSM Team, It would be great if you could delete a record via API. Thank you,

        • Instant Messaging Update | Now migrate your WhatsApp Business phonenumber from another BSP to Zoho Desk | Dec'23

          Hi All, Everything seems to move at lightning speed these days, and time is certainly flying by for the IM team. But we are delighted at how much ground we covered this year. 🚀 For one, we enabled WhatsApp business phone number migration so that you

        • Upload ticket attachments via Drag-&-Drop

          Hello, if you want to upload a file to the ticket attachment you need to click the button and use the file browser to select and upload the desired file. In many cases, it would be much more efficient if you could simply drag the file to the browser window...

        • Can we disable add to cart in Zoho Commerce?

          Hello, Our sales happen on the phone. During the call the customer is directed to our website to inspect the products together with the sales rep. So we need a way to present our inventory. I figured Zoho Commerce is a good fit for this use case. However

        • Introducing WhatsApp integration in Bigin

          Greetings! In today's business landscape, messaging apps play a significant role in customer operations. Customers can engage with businesses, seek support, ask questions, receive personalized recommendations, read reviews, and even make purchases—all

        • Issues with Zoho Sheet in Mac

          I have downloaded the Zoho App from App Store but It is failing to Save As, Open & Download Operations. App Store

        • Zoho One account closure vs deactivation

          I wonder what are the best practices and guidelines around deactivating vs deleting Zoho accounts in organisations? Any practical considerations?

        • Global Search placement in the new UI

          Having a hard time with the global search placement in the UI redesign. Surely I can't be the only one. Previously global search placement was perfect. A bar at the top/center of the page. Exactly where you would expect it to be. Since the new UI has

        • Role Management

          I am creating an analytics dashboard for a company that will be utilized by its various departments such as Finance, Marketing, and HR. My goal is to design the dashboard with separate tabs for each department. Additionally, I plan to implement role-based

        • Schedule Zoho CRM reports only on Business Days

          Hello, Is it possible to schedule reports only on business days ? We currently get daily sales reports on weekend which has no value since the sales team doesn't work on weekends. Thanks

        • How to install Widget in inventory module

          Hi， I am trying to install a app into Sales Order Module related list, however there is no button allow me to do that. May I ask how to install widget to inventory module related list?

        • Cannot see Application from Lookup field

          Hi all, I am trying to access data for an application on our account via a lookup field; however, the application doesn't appear in the dropdown at all. Can anyone shed any light on this, please? I have asked Zoho support; however, they're just as confused,

        • How to track a contact or customer's past product purchases in Bigin Premiere?

          Hello there. I am the sole user of Bigin for a small company (chess club), and would like to track current and past purchases made by a contact (player) or company (family which includes the player). Players may register for multiple tournaments, take

        • LENTITUD EN RECIBIR MAIL

          Buenas tardes, Estamos experimentando lentitud en la recepción de correos electrónicos.

        • Items should display under specific warehouse

          I have configured the multi warehouse but it show all the items under all warehouse which is not correct according to our business logic, so i want that items should only display under that specific warehouse not under all the warehouses not even with zero quantity. Some items should be common but not all so is there any option for that purpose so i can specific the items to its warehouse. Regards

        • Tracking Non-Inventory Items

          We have several business locations and currently use zoho inventory to track retail items (sales and purchase orders). We were hoping to use zoho inventory to track our non-inventory items as well (toilet paper, paper towels, etc). I understand that we

        • Partial refunds

          I am trying to process refund for a one item invoice, however the refund is partial: i am getting this error while creating credit note, can anyone share some wisdom about this

        • Best practice importing items and matching assemblies

          Hi, I was wondering what would be the best practice to import items and composite items (assemblies) From my backup, what should I import first? The items or the composite items? I am on Zoho one, using inventory and books. Kind regards, Sabine

        • Bulk Fill In & Edit PO/Bill/SO/Invoice

          Hello, I am adding stock in bulk on a PO, the system is automatically populating the Rate (price) and Tax from the item data. Problem is that the bill rate is different from the rate on the item data, so I have to manually erase each and enter the price.

        • Separate Items & Services

          Hi, please separate items and services into different categories. Thank you

        • Items Below Reorder Point Report?

          Is there a way to run a report of Items that are below the Reorder Point? I don't see this as a specific report, nor can I figure out how to customize any of the other stock reports to give me this information. Please tell me I'm missing something s

        • Allocating inventory to specific SO's

          Is there a way that allocate inventory to a specific sales order? For example, let's say we have 90 items in stock. Customer 1 orders 100 items. This allocates all 90 items to their order, and they have a back order for the remaining 10 items which could

        • Cancelled Transfer order problem

          Hello, We've canceled a transfer order, and we can't add the related items to a new Transfer Order. The system tells us that the bin doesn't have the required quantity, but when we check the item, it indicates that there are 2 units in the bin. It also

        • Creating a Chart from a Report

          In Zoho Analytics, is it possible to create a chart from a Pivot View report? We are looking to use Zoho Analytics to replace Excel for Sales reports and would like to be able to show both the table and the chart together.

        • Client Portal ZOHO ONE

          Dear Zoho one is fantastic option for companies but it seems to me that it is still an aggregation of aps let me explain I have zoho books with client portal so client access their invoice then I have zoho project with client portal so they can access their project but not their invoice without another URL another LOGIN Are you planning in creating a beautiful UI portal for client so we can control access to client in one location to multiple aps at least unify project and invoice aps that would

        • Email Insights included in Bigin emals are marked as SPAM everywhere

          Today I noticed that email recipients who use Office 365 never receive emails sent from Bigin. Further examination showed that all Email Insights links in email headers are marked as spam/phishing by Office 365. Example screen included. The problem is

        • Data Import | Zoho Analytics Custom Query Window Size

          Please increase the window size for the Custom Query Data Import. It's impossible to work with such a small query window.

        • Next Page