Track LLM token costs per customer using the Langchain code node

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Important notice

This workflow is provided as-is. Please review and test before using in production.

1. Workflow Overview

Note: This template only works for self hosted n8n. This n8n te...

Best for

Engineering automation workflows
AI Summarization automation workflows
advanced n8n builders looking for reusable templates

Tools used

n8n-nodes-base.googlesheetstool, n8n-nodes-base.set, n8n-nodes-base.formtrigger, @n8n/n8n-nodes-langchain.code, n8n-nodes-base.stickynote, n8n-nodes-base.form, n8n-nodes-base.filter, n8n-nodes-base.googlesheets

Source and attribution

This workflow is cataloged by N8N Workflows and links back to its original n8n.io source page by Jimleuk.

Original n8n.io source

1.1 Workflow description

Title: Track LLM token costs per customer using the Langchain code node
Workflow name: Track LLM token costs per customer using the Langchain code node

Note: This template only works for self-hosted n8n.

This n8n template demonstrates how to use the Langchain code node to track token usage and cost for every LLM call.

This is useful if your templates handle multiple clients or customers and you need a cheap and easy way to capture how much of your AI credits they are using.

How it works

In our mock AI service, we're offering a data conversion API to convert Resume PDFs into JSON documents.
A form trigger is used to allow for PDF upload and the file is parsed using the Extract from File node.
An Edit Fields node is used to capture additional variables to send to our log.
Next, we use the Information Extractor node to organise the Resume data into the given JSON schema.
The LLM subnode attached to the Information Extractor is a custom one we've built using the Langchain Code node.
With our custom LLM subnode, we're able to capture the usage metadata using lifecycle hooks.
We've also attached a Google Sheet tool to our LLM subnode, allowing us to send our usage metadata to a google sheet.
Finally, we demonstrate how you can aggregate from the google sheet to understand how much AI tokens/costs your clients are liable for.

Check out the example Client Usage Log - https://docs.google.com/spreadsheets/d/1AR5mrxz2S6PjAKVM0edNG-YVEc6zKL7aUxHxVcffnlw/edit?usp=sharing

How to use

SELF-HOSTED N8N ONLY - the Langchain Code node is only available in the self-hosted version of n8n. It is not available in n8n cloud.
The LLM subnode can only be attached to non-"AI agent" nodes; Basic LLM node, Information Extractor, Question & Answer Chain, Sentiment Analysis, Summarization Chain and Text Classifier.

Requirements

Self-hosted version of n8n
OpenAI for LLM
Google Sheets to store usage metadata

Customising this template

Bring the custom LLM subnode into your own templates! In many cases, it can be a drop-in replacement for the regular OpenAI subnode.
Not using Google Sheets? Try other databases or a HTTP call to pipe into your CRM.

1.2 Logical Blocks

This catalog entry is organized from the workflow JSON. The node-level section below shows the executable blocks available for review before importing the template.

2. Block-by-Block Analysis

Block 1 - Client Usage Log

Type / Role: n8n-nodes-base.googleSheetsTool - googleSheetsTool
Config choices: Version 4.5

Block 2 - Logging Attributes

Type / Role: n8n-nodes-base.set - set
Config choices: Version 3.4

Block 3 - On form submission

Type / Role: n8n-nodes-base.formTrigger - formTrigger
Config choices: Version 2.2

Block 4 - Custom LLM Subnode

Type / Role: @n8n/n8n-nodes-langchain.code - code
Config choices: Version 1

Block 5 - Sticky Note

Type / Role: n8n-nodes-base.stickyNote - stickyNote
Config choices: Version 1

Block 6 - Sticky Note1

Type / Role: n8n-nodes-base.stickyNote - stickyNote
Config choices: Version 1

Block 7 - Sticky Note2

Type / Role: n8n-nodes-base.stickyNote - stickyNote
Config choices: Version 1

Block 8 - Sticky Note3

Type / Role: n8n-nodes-base.stickyNote - stickyNote
Config choices: Version 1

Block 9 - Sticky Note4

Type / Role: n8n-nodes-base.stickyNote - stickyNote
Config choices: Version 1

Block 10 - Display JSON Document

Type / Role: n8n-nodes-base.form - form
Config choices: Version 1

Block 11 - Filter Last Month

Type / Role: n8n-nodes-base.filter - filter
Config choices: Version 2.2

Block 12 - Get Client Logs

Type / Role: n8n-nodes-base.googleSheets - googleSheets
Config choices: Version 4.5

Block 13 - Calculate Totals

Type / Role: n8n-nodes-base.summarize - summarize
Config choices: Version 1.1

Block 14 - Every End of Month

Type / Role: n8n-nodes-base.scheduleTrigger - scheduleTrigger
Config choices: Version 1.2

Block 15 - Send Invoice

Type / Role: n8n-nodes-base.gmail - gmail
Config choices: Version 2.1

Block 16 - Sticky Note5

Type / Role: n8n-nodes-base.stickyNote - stickyNote
Config choices: Version 1

Block 17 - Sticky Note6

Type / Role: n8n-nodes-base.stickyNote - stickyNote
Config choices: Version 1

Block 18 - Sticky Note7

Type / Role: n8n-nodes-base.stickyNote - stickyNote
Config choices: Version 1

Block 19 - Parse PDF Upload

Type / Role: n8n-nodes-base.extractFromFile - extractFromFile
Config choices: Version 1

Block 20 - Extract Resume Data

Type / Role: @n8n/n8n-nodes-langchain.informationExtractor - informationExtractor
Config choices: Version 1

3. Summary Table

Workflow	Track LLM token costs per customer using the Langchain code node
Complexity	advanced
Nodes	20
Categories	Engineering, AI Summarization
Author	Jimleuk
Published	05 Apr 2025

4. Reproducing the Workflow from Scratch

1. Download the workflow JSON

Use the JSON export at /data/workflows/3440/3440.json as the source template for this automation.
2. Import the template into n8n

Open n8n, import the downloaded JSON, and review each node before activating the workflow.
3. Configure credentials and variables

Replace placeholder credentials, API keys, webhook URLs, account IDs, and environment-specific values with your own settings.
4. Test with sample data

Run the workflow manually or in a staging workspace, inspect node output, and confirm downstream systems receive the expected data.
5. Activate and monitor

Enable the workflow only after testing, then monitor executions, errors, and rate limits during the first production runs.

5. General Notes & Resources

Review imported nodes carefully before activation. This catalog entry is intended to help you inspect the workflow structure, understand required services, and find related templates faster.

Node names, credentials, schedules, webhook paths, and external service limits may need adjustment for your workspace.

Download workflow JSON Original n8n.io source Engineering workflows AI Summarization workflows

Frequently asked questions

What does Track LLM token costs per customer using the Langchain code node do?

Note: This template only works for self hosted n8n. This n8n te...

What do I need before importing this workflow?

Review the workflow JSON, configure any required credentials in n8n, and test the automation in a safe workspace before using it in production.

Can I customize this workflow?

Yes. Use the block-by-block analysis and the downloadable JSON to inspect each node, then adjust credentials, prompts, schedules, filters, or destinations for your Engineering, AI Summarization use case.

Jimleuk

100 workflows

Nodes

n8n-nodes-base.googlesheetstool n8n-nodes-base.set n8n-nodes-base.formtrigger @n8n/n8n-nodes-langchain.code n8n-nodes-base.stickynote n8n-nodes-base.form n8n-nodes-base.filter n8n-nodes-base.googlesheets

Complexity

advanced

Published 05 Apr 2025

Likes 0

View on n8n.io Download Workflow

Install path: /data/workflows/3440/3440.json

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Track LLM token costs per customer using the Langchain code node

Workflow preview

Important notice

1. Workflow Overview

Best for

Tools used

Source and attribution

1.1 Workflow description

This n8n template demonstrates how to use the Langchain code node to track token usage and cost for every LLM call.

How it works

How to use

Requirements

Customising this template

1.2 Logical Blocks

2. Block-by-Block Analysis

Block 1 - Client Usage Log

Block 2 - Logging Attributes

Block 3 - On form submission

Block 4 - Custom LLM Subnode

Block 5 - Sticky Note

Block 6 - Sticky Note1

Block 7 - Sticky Note2

Block 8 - Sticky Note3

Block 9 - Sticky Note4

Block 10 - Display JSON Document

Block 11 - Filter Last Month

Block 12 - Get Client Logs

Block 13 - Calculate Totals

Block 14 - Every End of Month

Block 15 - Send Invoice

Block 16 - Sticky Note5

Block 17 - Sticky Note6

Block 18 - Sticky Note7

Block 19 - Parse PDF Upload

Block 20 - Extract Resume Data

3. Summary Table

4. Reproducing the Workflow from Scratch

1. Download the workflow JSON

2. Import the template into n8n

3. Configure credentials and variables

4. Test with sample data

5. Activate and monitor

5. General Notes & Resources

Frequently asked questions