Permit is an access control platform that provides fine-grained, real-time permission management using various models such as RBAC, ABAC, and ReBAC. It enables organizations to enforce dynamic policies across their applications, ensuring that only authorized users can access specific resources.

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Overview

This package provides two Langchain tools for JWT validation and permission checking using Permit:
  • LangchainJWTValidationTool: Validates JWT tokens against a JWKS endpoint
  • LangchainPermissionsCheckTool: Checks user permissions using Permit

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Setup

Set up the following environment variables: 
PERMIT_API_KEY=your_permit_api_key
JWKS_URL=your_jwks_endpoint_url
PERMIT_PDP_URL=your_permit_pdp_url  # Usually http://localhost:7766 for local development or your real deployment
Make sure your PDP (Policy Decision Point) is running at PERMIT_PDP_URL. See Permit docs for details on policy setup and how to launch the PDP container.

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Credentials

PERMIT_API_KEY=
JWKS_URL=your_jwks_endpoint_url # or your deployed url
PERMIT_PDP_URL=your_pdp_url # or your deployed url
TEST_JWT_TOKEN= # for quick test purposes
It’s also helpful (but not needed) to set up LangSmith for best-in-class observability:

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Instantiation

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JWT Validation Tool

The JWT Validation tool verifies JWT tokens against a JWKS (JSON Web Key Set) endpoint. 
from langchain_permit.tools import LangchainJWTValidationTool

# Initialize the tool
jwt_validator = LangchainJWTValidationTool(
    jwks_url=#your url endpoint
)

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Configuration Options

You can initialize the tool with either:
  • A JWKS URL
  • Direct JWKS JSON data
  • Environment variable (JWKS_URL)
# Using direct JWKS JSON
jwt_validator = LangchainJWTValidationTool(
    jwks_json={
        "keys": [
            {
                "kid": "key-id",
                "kty": "RSA",
                ...
            }
        ]
    }
)

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Permissions Check Tool

The Permissions Check tool integrates with Permit.io to verify user permissions against resources. 
from permit import Permit
from langchain_permit.tools import LangchainPermissionsCheckTool

# Initialize Permit client
permit_client = Permit(
    token="your_permit_api_key",
    pdp=# Your PDP URL
)

# Initialize the tool
permissions_checker = LangchainPermissionsCheckTool(
    permit=permit_client
)
This documentation demonstrates the key features and usage patterns of both tools.

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Invocation

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Invoke directly with args

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JWT Validation Tool

# Validate a token
async def validate_token():
    claims = await jwt_validator._arun(
        "..."  # Your JWT token
    )
    print("Validated Claims:", claims)

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Permissions Check Tool

# Check permissions
async def check_user_permission():
    result = await permissions_checker._arun(
        user={
            "key": "user-123",
            "firstName": "John"
        },
        action="read",
        resource={
            "type": "Document",
            "tenant": "default"
        }
    )
    print("Permission granted:", result)

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Input Formats

The permissions checker accepts different input formats:
  1. Simple string for user (converts to user key):
result = await permissions_checker._arun(
    user="user-123",
    action="read",
    resource="Document"
)
  1. Full user object:
result = await permissions_checker._arun(
    user={
        "key": "user-123",
        "firstName": "John",
        "lastName": "Doe",
        "email": "john@example.com",
        "attributes": {"department": "IT"}
    },
    action="read",
    resource={
        "type": "Document",
        "key": "doc-123",
        "tenant": "techcorp",
        "attributes": {"confidentiality": "high"}
    }
)

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Invoke with ToolCall

(TODO)

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Chaining

  • TODO: Add user question and run cells
We can use our tool in a chain by first binding it to a tool-calling model and then calling it:

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Additional Demo Scripts

For fully runnable demos, check out the /langchain_permit/examples/demo_scripts folder in this repository. You’ll find:
  • demo_jwt_validation.py – A quick script showing how to validate JWTs using LangchainJWTValidationTool.
  • demo_permissions_check.py – A script that performs Permit.io permission checks using LangchainPermissionsCheckTool.
Just run python demo_jwt_validation.py or python demo_permissions_check.py (after setting your environment variables) to see these tools in action.

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API reference

For detailed documentation of all Permit features and configurations head to the API reference: https://docs.permit.io/