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

    • Remove 'This is an automated mail from Zoho Sign' in footer

      Hi there, Is it possible to remove or change the text under the e-mail templates? I can't figure out how to do that: Would love to hear from you. Kind regards, Tristan

    • Passing Info from Function to Client Script

      Hello, I have recently started making use of client script for buttons, allowing me to give the user information or warnings before they proceed. This is great. However, I have never quite managed to pass back any extra information from the function to

    • Drag 'n' Drop Fields to a Sub-Form and "Move Field To" Option

      Hi, I would like to be able to move fields from the Main Page to a Sub-Form or from a Sub-Form to either the Main Page or another Sub-Form. Today if you change the design you have to delete and recreate every field, not just move them. Would be nice to

    • Zoho Payroll for Canada

      Is anyone else having problems getting setup for Canada?

    • Passing the CRM

      Hi, I am hoping someone can help. I have a zoho form that has a CRM lookup field. I was hoping to send this to my publicly to clients via a text message and the form then attaches the signed form back to the custom module. This work absolutely fine when

    • One Contact with Multiple Accounts with Portal enabled

      I have a contact that manages different accounts, so he needs to see the invoices of all the companies he manage in Portal but I found it not possible.. any idea? I tried to set different customers with the same email contact with the portal enabled and

    • User Automation: User based workflow rules & webhooks

      User management is an undeniable part of project management and requires adequate monitoring. As teams grow and projects multiply, manual coordination for updating users & permissions becomes difficult and can give way to errors. User automation in Zoho

    • Default Ticket View - Table?

      Guys, We mostly use the table view to queue tickets. Maybe I am missing it - but how can I set that view as 'default" for all our agents? Thanks JV

    • Zoho One IS BUGGY

      Here are some things that just don't work: - Disabling applications from certain Spaces - Adding users (probably only for me) - Renaming applications in Zoho One Portal (fixed by now) - Reordering applications in Spaces When I try to reorder: It feels

    • Merge Fields that previously worked are now giving an Error!

      Saving a URL Link button on the Deal module. The below fields used to save without issue at all, but now produce an error of "URL contains unsupported merge field!" ${Contacts.Mailing Street} ${Contacts.Mailing City} ${Contacts.Mailing State} ${Contacts.Mailing

    • Clarification on Zoho Forms 1-User Plan: Multiple Submitters and Approvers

      Question Content (Copy–Paste Ready) Hello Zoho Team, I would like clarification regarding Zoho Forms pricing and user limits. I am planning to subscribe to the ₹700/month (1 user) plan. My use case is as follows: Only 1 person (myself) will create and

    • App for Mac OS X please!

      It would be awesome to have a mail app for Mac OS X that included all the cool features such as steams, calendar, tasks, contacts, etc. Most people prefer native apps, rather than running it through a web browser. I know that we can use the IMAP, CalDAV,

    • Facing Issues with Sites Mobile font sizes

      my page renediaz.com is facing issues mobile view, when i try to lower font sizes in home page, instead of changing the size, it changes the line space

    • Zoho Books Payroll

      How am I supposed to do payroll and pay my employees with Zoho Books? I think it's pretty strange that an accounting software doesn't have the ability to perform one of the most common functions in business; paying your employees. Am I missing something,

    • Canvas templates can now be shared with different CRM organizations

      ----------------------------------------Moderated on 14th February, 2023------------------------------------------- Dear all, This feature is now open for all users in all DCs. To learn more about importing and exporting canvas templates, read our help

    • Change Last Name to not required in Leads

      I would like to upload 500 target companies as leads but I don't yet have contact people for them. Can you enable the option for me to turn this requirement off to need a Second Name? Moderation update (10-Jun-23): As we explore potential solutions for

    • creating an alias

      your instructions for creating an alias are wrong. there is no add alias in my mail account. also i dont have a control panel link just a settings link how do i really make an alias

    • Reply to Email for SO/PO

      Hello, We are new to Zoho Books and running into an issue. Our support@ email is our integration user. When our team is sending out PO/SO's we are updating the sender email, but for some reason many of our responses are coming back to our support@ email

    • ZOHO Payroll Canada

      Any plans on the roadmap for Canada?

    • Zoho Books Sandbox environment

      Hello. Is there a free sandbox environment for the developers using Zoho Books API? I am working on the Zoho Books add-on and currently not ready to buy a premium service - maybe later when my add-on will start to bring money. Right now I just need a

    • Multi-currency and Products

      One of the main reasons I have gone down the Zoho route is because I need multi-currency support. However, I find that products can only be priced in the home currency, We sell to the US and UK. However, we maintain different price lists for each. There

    • ZOHO Writer Folders

      Hi We would love to have ability to create folders on the left hand side. We would then be able create and store our documents within each folder Hope you can provide this feature soon ! dux.centra

    • How can Data Enrichment be automatically triggered when a new Lead is created in Zoho CRM?

      Hi, I have a pipeline where a Lead is created automatically through the Zoho API and I've been trying to look for a way to automatically apply Data Enrichment on this created lead. 1) I did not find any way to do this through the Zoho API; it seems like

    • Escalation request: organization merge and data export (Ticket [154609577])

      Hello Zoho Team, I am posting here because my support ticket has not received substantive responses through the usual channels. Summary of the issue (ongoing for three weeks): I requested assistance with a data migration and a merge of two Zoho organizations.

    • Different form submission results for submitter and internal users

      I'm looking for suggestions on how to show an external submitter a few results while sending internal users all the results from the answers provided by the external user. The final page of our form has a section with detailed results and a section with

    • Formatting and slow

      Creating campaigns are difficult.  I'm fairly computer literate but some of the way Zoho Campaigns formatting works is painful.  Images fail to upload or are very slow. To top it off, syncing the contacts is a pain as well as temperamental links to create Segments. At this rate I'm afraid we might need to migrate back to Mailchimp.

    • Boost your Zoho Desk's performance by archiving tickets!

      The longer your help desk operations are, the more likely it is to accumulate tickets that are no longer relevant. For example, ticket records from a year ago are typically less relevant than currently open tickets. Such old tickets may eventually lead

    • Paste emails to create segment

      We are moving over from Mailchimp to ZOHO. However Mailchimp allows me to create a segment by pasting in emails from excel (or importing a .csv) can I do the same in Mailchimp?

    • Getting the Record ID of a form once it is submitted - so that form can be edited later

      In Zoho Forms, where can I access the record ID of a form once the form is submitted? - Record ID is not available in webhook payloads - It is not available to form fields, including in formulas - It is not available as a parameter in a thankyou page

    • Possible to define default font and size in Zoho Campaigns?

      Is it possible to define a default font (font, size and colour) for the text, H1 and H2 in Zoho Campaigns? For example: In a campaign, I add a text block, and the text is automatically century gothic, size 11, grey (6f6f6e) by default? Thank you!

    • Zoho Sites - General Feedback

      Hi Everyone-- Quick question for discussion: is it me or is working with Zoho Sites like entering the Twilight Zone? I've built many sites over the years, but this platform seems impossible. I've spent an entire day and a half trying to get a simple one-color

    • Zoho People & Zoho CRM Calendar

      Hi, Does anyone know if it is possible to link Zoho People and the calendar in CRM? I would like when holidays are approved they automatically appear in the calendar on CRM. Thanks 

    • File Upload field not showing in workflow

      Hi, I have added a field on Zoho CRM. I want to use it in a workflow where that particular field is updated based on another field, however it is not showing up in the field list to select it in the workflow. Why is this please?

    • You cannot send this email campaign as it doesn't have any eligible contacts in the selected mailing list. You can try adding contacts or choose other mailing lists.

      please help

    • Strengthening the capabilities of CommandCenter in Zoho CRM Plus

      When you look at the prospect-to-customer journey in most businesses 10 to 15 years ago, it was relatively straightforward. Many of us remember walking into a store, sharing our requirements with a sales associate, reviewing a few options, and making

    • Any recommendations for Australian Telephony Integration providers?

      HI,  I am looking for some advice on phone providers as we are looking to upgrade our phone system, does anybody have experience with any of the Australian providers that integrate with CRM Telephony? So far we are looking at RingCentral and Amazon Connect, and would love to hear feedback on any of the other providers you might have tried.  Thank you

    • Zoho Campaigns Workspaces

      Hi, I’m currently working on a Zoho CRM + Zoho Campaigns setup for a franchisee-based organization, where each franchise must only see and use its own contacts. At the moment, franchisees cannot properly access their contact lists in Zoho Campaigns unless

    • Newsletter in multiple languages

      Hi We are planning on starting to use Zoho Campaigns for our newsletters. Since we send our newsletters in three languages, I would need the "unsubscribe page" and other pages related to the NL (Thank you page and so on) to be available in different languages

    • Fixed assets in Zoho One?

      Hi, We use Zoho Books and have the fixed asset option in it. I started a trial for Zoho One and I do not see that as an option. Is the books that is part of zoho one equivalent to Zoho Books Elite subscription or is it a lesser version? Thanks, Matt

    • Set Default Status of Assembly to "Assembled" When Entered in UI

      I've just discovered the new "confirmed" status of Assemblies within Inventory. While I understand the intent of this (allowing for manufacturing planning and raw material stock allocation), it was initially confusing to me when manually entering some

    • Next Page