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

    • Condition based aggregate fields in subforms

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

    • SalesInbox

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

    • Print labels on selected view

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

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

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

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

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

    • Printing Client Lists

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

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

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

    • ZOHO Blueprint and Workflow

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

    • Zoho CRM Participants Automatic - Invite Using Deluge

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

    • Greek character in Deluxe script

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

    • Work Order Assignment for Engineers Handling Their Own Requests

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

    • Experience Zoho Show on Mac now!

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

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

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

    • Kiosk Button Actions

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

    • Dependent drop-downs... how?

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

    • Reporting Limitation on Lead–Product Relation in Zoho CRM

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

    • Series Label in the Legend

      My legend reads 'Series 1' and 'Series 2'. From everything I read online, Zoho is supposed to change the data names if it's formatted correctly. I have the proper labels on the top of the columns and the right range selected. I assume it's something in

    • Dynamic Signature - Record owner

      Hi everyone, I’m using Zoho Writer merge templates from Zoho CRM and have two questions: Owner signature: How can I automatically insert the CRM record owner’s signature in the merged document? I’m not sure where this signature is stored or how to reference

    • Set Warehouse based on Vendor

      Greetings. I would like to set automaticaly the Warehouse based on the Vendor. Context: I am working on an adaptation of a Purchase Order to be used as a Quotation. I have defined that when a user has to raise a quote the Vendor will be "PROCUREMENT" I would like to set the Warehouse to a predefined value when "PROCUREMENT" is set as Vendor. I have tried to do with the Automation feature using the Field Update option, but Warehouse does not is listed as a field. Can you help? Thanks in advance.

    • Printing from Zoho Creator hosted on my own server to printers hosted on my clients local network

      Hello. Fairly new to Zoho Creator and looking for best options to be able to print from my application hosted on my own server to any printer hosted on my clients own local network. Any advice is welcome. Thank you.

    • Add System Pre-Defined Lookup Field to Subform?

      Hi there! New to using Zoho, so this may already exist, but I'm having trouble figuring it out. Is there a way to get the system pre-defined Account Lookup field (in our case, renamed to Company Name), as the starting point for a subform? In our company,

    • Numbered / bullet point List in Zho Cliq

      Hi, is there a way to format chat messages in Cliq like this Topic 1 Hey, I finished this project yesterday etc... Topic 2 I am still working on this etc...

    • Cannot Access Subform Display Order in Deluge

      As highlighted in this community post, we still have to deal with the significant limitation of not being able to access the user-sorted order of subform rows through Deluge. This creates a major disconnect between the UI capabilities and backend automation,

    • How many groups in Zoho Mail can I make?

      I'm currently on the free plan, which has a limit of 10 users. Does that limit includes groups too? If not, what is the limit for groups? Thanks!

    • Feature Suggestion for Zoho Social: Auto-reply to Comments or Keywords

      Hi Zoho team, I'd like to suggest a very specific feature that would be extremely helpful for customer engagement: the ability to automatically send a reply to comments on posts — either all comments or those containing specific keywords. For example,

    • Already have Zoho account. Not letting me log in

      I already have a Zoho account that is associated with my Google email and my phone number. Even though I'm already logged in to Zoho, when I click on the mail icon to access my email, it takes me to the pricing page. When I click on the free option, it

    • ZOHO Mail App Not working

      There seems to be an issue with Zoho Mail App today. It is not connecting to server, internet is working fine, tried uninstalling app and reinstalling, loading circle keeps spinning round. Is there an update on the way?

    • facing error 550 5.4.6 while sending emails

      Please help me fix this issue

    • Allow Itemization for Recurring Expenses

      For whatever reason, one cannot itemize a Recurring Expense. This capability should be added. The use cases to support this are largely the same as what they were to allow for itemization in Expenses. Anything that would need to be itemized for a regular

    • Zoho reply to not working. just reply to my self

      Hello. i using on my wordpress website a contact form from Wsform. i can set the reply to email there. normally it works. but since i am using your wordpress plugin zoho mail it doesn`t work. its not using the reply to (email from customer). I just can

    • Can't receive any email from other platform

      Hello,everyone, i'm just join zoho and create two email accounts for my own business. I was using it to get a verified email from stripe, but can't receive it. and I use my private gmail account to send test email twice, first time show below reply, but

    • Your Incoming has been blocked and the emails will not be fetched in your Zoho account and POP Accounts

      Can some on help me regarding our account . thank you so much

    • Zoho Creator integration with Sage 50

      Hi, Wondering if anyone has had any experience connecting Zoho to Sage 50 and could share any information on this matter. Thank you.

    • Conditional Email Forwarding

      How can I set conditional email forwarding of the users? For example: Mail should be forwarded to a address only if it comes from a particular sender. So, I want such email forwarding, which forwards mails based on particular conditions, like the incoming

    • Incoming emails not appearing in Inbox

      Hello, I have an issue with incoming emails sent from my website (domain: h2ostop.si). Emails are visible in the Sent folder, which means they are successfully sent through Zoho SMTP, but they never appear in my Inbox. Nothing arrives in Inbox, Spam,

    • 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

    • Email Opt Out Question

      Has the problem where if a customer is emailed opt out prevents you sending standard emails? For me this feature is simply to stop any email marketing and should not block people from receiving emails via Zoho mobile, which makes no sense.

    • Can No Longer Access Zoho Email Accounts from iPhone or iPad Apple Mail Apps ,.

      Keeps asking for password, Says ID or password incorrect. Tried creating a new app specific password. Same result. Is this possibly related to the server maintenance. Have verified all email settings, userid and password. This has worked for years until

    • Latest update caused issue in using marathi typingzoho

      With latest update now marathi typing does Not work in zohonotebook. I preferred zoho over other because it was supporting marathi font without any distortion.. But after new update,keyborad simply does not work

    • Login verification emails never received.

      I can't login to my account. You send a verification email, but it never arrives. This is a common problem, frequently caused by some relay point out there classifying the sender as a spammer. Is there anything I can do to bypass this? Maybe get a text

    • Next Page