What port does TallyPrime use for XML API communication?

TallyPrime runs an XML-RPC server listening on TCP Port 9000 by default. You can configure this port in Tally's Connectivity settings under Help > Settings > Connectivity.

Can I add custom buttons or modify screen layouts in TallyPrime using the XML API?

No. The XML API is strictly a data bridge for reading and writing data records. To modify the TallyPrime user interface, add custom buttons, or restrict specific input fields, you must write a TDL (Tally Definition Language) program.

How do I format a debit ledger entry versus a credit ledger entry in Tally XML?

Tally's XML engine uses signs to define debit and credit. Debit ledger entries must have a negative value in the tag (e.g. -1500.00 ) and Yes set. Credit ledger entries must have a positive value in the tag (e.g. 1500.00 ) and No .

Do I need a separate developer license to write TDL code?

To write basic TDL, you can use any text editor and compile the script inside TallyPrime. However, for advanced development, creating encrypted TCP files, or publishing add-ons, you need Tally Developer, a specialized IDE provided by Tally Solutions.

How does TrulyInvoice connect to Tally without requiring custom TDL development?

TrulyInvoice uses a pre-configured connector client that leverages Tally's native XML APIs. This allows you to sync data directly to Tally Prime without writing complex TDL code, managing compilation updates, or hiring specialized TDL developers.

Tally API vs TDL Customization [Technical Integration Guide 2026]

Integrating custom software (e-commerce storefronts, CRMs, custom billing systems) with TallyPrime can be achieved via the native XML API (outside-in) or custom TDL scripts (inside-out). Let's evaluate both approaches.

As businesses scale, connecting local accounting systems with digital sales, purchase, and inventory channels becomes essential. Choosing the right integration architecture for TallyPrime is key to building a reliable system. Development teams can choose between two main methods: the Tally XML API (an external integration bridge) and Tally Definition Language (TDL) (internal ERP scripting). This guide covers the technical details, benefits, limitations, and best use cases for both approaches.

Quick Answer: What is the Difference Between Tally XML API and TDL Customization (2026)?

TrulyInvoice leverages Tally's native HTTP XML API over Port 9000 to push F9 purchase vouchers directly into Tally Prime without modifying Tally source code or deploying custom TDL files.

Tally XML API operates over local HTTP Port 9000 to read/write voucher and ledger records.
TDL (Tally Definition Language) modifies Tally UI screens, menus, and custom fields inside Tally.
XML API requires zero TDL code compilation or version lock-ins.
TrulyInvoice local connector communicates with Tally Prime XML server automatically.

Direct Architectural Comparison

The primary difference between the XML API and TDL is where your application logic runs. The XML API is an 'outside-in' approach, while TDL is an 'inside-out' approach.

1. Tally XML API (Outside-In Approach)

The XML API allows external software applications (written in Python, Node.js, C#, PHP, etc.) to exchange data payload envelopes with TallyPrime over local TCP Port 9000.

Development Stack: Standard REST/HTTP request libraries in any programming language.
Pros: No need to learn proprietary TDL code; easy to maintain; decoupled from Tally's internal codebase.
Cons: Cannot alter Tally's user interface, add custom input fields, or restrict user actions inside Tally screens.

2. TDL Customization (Inside-Out Approach)

TDL is Tally's proprietary object-oriented definition language. It allows developers to add custom input fields, alter print invoice formats, build custom reports, and trigger external webhooks.

Development Stack: Restricted to Tally Definition Language (TDL) and the Tally Developer IDE.
Pros: Modify Tally's user interface, add custom input fields, create menu screens, and build custom internal reports.
Cons: Steep learning curve, single-threaded execution, and ongoing maintenance overhead to ensure compatibility with new TallyPrime releases.

Integration Comparison Matrix

Evaluation Metric	Tally XML API	TDL Customization
Supported Languages	Language-agnostic (HTTP/JSON/XML)	TDL Only
User Interface Mod	Not Possible	Full Control (Menus, Buttons, Forms)
Database Access	Read/Write via XML requests	Direct memory/table execution
Upgrade Risk	Low (API contracts rarely change)	High (Upgrades can break scripts)
Best Use Case	E-Commerce, Cloud sync, automated data import	Custom print invoices, internal audit workflows

Testing Tally's XML API

To test if TallyPrime's XML API server is active and responding, you can send an HTTP POST request using a standard tool like curl or Postman.

Run the following command in your terminal to request active company metadata from Tally Prime:

curl -X POST -H "Content-Type: text/xml" -d '<?xml version="1.5"?><ENVELOPE><HEADER><TALLYREQUEST>Export Data</TALLYREQUEST></HEADER><BODY><EXPORTDATA><REQUESTDESC><REPORTNAME>List of Companies</REPORTNAME><STATICVARIABLES><SVEXPORTFORMAT>$$SysName:XML</SVEXPORTFORMAT></STATICVARIABLES></REQUESTDESC></EXPORTDATA></BODY></ENVELOPE>' http://localhost:9000

Programmatic Querying via Python

For web development, Python's requests package makes sending XML envelopes straightforward. The script below sends a ledger export query to TallyPrime and prints the parsed response:

import requests

url = "http://localhost:9000"
headers = {"Content-Type": "text/xml"}

xml_payload = """<?xml version="1.5"?>
<ENVELOPE>
  <HEADER>
    <TALLYREQUEST>Export Data</TALLYREQUEST>
  </HEADER>
  <BODY>
    <EXPORTDATA>
      <REQUESTDESC>
        <REPORTNAME>Trial Balance</REPORTNAME>
        <STATICVARIABLES>
          <SVEXPORTFORMAT>$$SysName:XML</SVEXPORTFORMAT>
        </STATICVARIABLES>
      </REQUESTDESC>
    </EXPORTDATA>
  </BODY>
</ENVELOPE>"""

try:
    response = requests.post(url, data=xml_payload, headers=headers)
    if response.status_code == 200:
        print("Export successful!")
        print(response.text[:500])  # Print first 500 characters
    else:
        print(f"Server returned status: {response.status_code}")
except requests.exceptions.ConnectionError:
    print("Connection Failed. Ensure TallyPrime is active and Port 9000 is open.")

Security Challenges in Local XML APIs

The TallyPrime XML-RPC server is designed for local intranet use and has limited built-in security features. The API server does not support native token authentication (like OAuth2 or Bearer keys) or Cross-Origin Resource Sharing (CORS) limits out of the box.

This means any script running on your local network can query your financial database if Port 9000 is open. To secure your setup:

Configure Windows Defender Firewall to block external incoming requests on Port 9000, limiting traffic to 127.0.0.1 (localhost) unless network sharing is required.
Avoid exposing Tally's local server port directly to the internet using router DMZ or port-forwarding rules.
If cloud access is needed, use a secure VPN tunnel or reverse proxy client with API key authentication to handle requests safely.

Bypassing Integration Complexity with TrulyInvoice

Developing custom TDL scripts or managing complex XML-RPC clients requires specialized technical resources. In-house integrations often suffer from sync errors, slow processing times, and high maintenance costs when TallyPrime releases are updated.

By implementing TrulyInvoice, you can avoid this development overhead. TrulyInvoice's cloud platform handles data extraction, mapping, and validation. It communicates directly with TallyPrime's native XML engine using our secure local connector, providing a reliable, out-of-the-box integration without the need for custom coding or TDL maintenance.

Tally API Integration vs. TDL Customization: B2B Integration Guide