Before starting the data migration, familiarize yourself with Railz's API documentation and the data structure you plan to move. Identify the endpoints from which you need to fetch data, the types of data available, and any authentication requirements.

Create a Python script to access the Railz API. Use Python's `requests` library to handle HTTP requests. Ensure you have the necessary API keys or tokens for authentication. Start by writing a function that fetches data from the required endpoint(s).

```python
import requests

def fetch_data_from_railz(url, headers):
response = requests.get(url, headers=headers)
return response.json()
```

Once you've fetched the data, extract the required information and transform it into a format suitable for Redis. This may involve cleaning the data, converting data types, or restructuring JSON objects to match your Redis storage strategy.

Ensure you have a running Redis server. You can install Redis locally or use a cloud-based service. Confirm that you can connect to your Redis instance using a Redis client, such as `redis-py`.

```bash
# Start Redis server (if running locally)
redis-server
```

Use the `redis-py` library to establish a connection to your Redis server from your Python script. Define a function to set data in Redis. You may choose to store data as strings, hashes, sets, or lists depending on your data structure requirements.

```python
import redis

def connect_to_redis(host='localhost', port=6379):
return redis.StrictRedis(host=host, port=port, decode_responses=True)

def store_data_in_redis(redis_client, key, value):
redis_client.set(key, value)
```

Create a mapping strategy between Railz data and Redis keys. Iterate over the fetched data, apply any necessary transformations, and store each piece in Redis using the defined mapping. Use the `store_data_in_redis` function to save each data entry.

```python
def transfer_data(railz_data, redis_client):
for item in railz_data:
# Example: map 'id' from Railz data to Redis key
key = f"railz_data:{item['id']}"
value = item['data'] # Transform as needed
store_data_in_redis(redis_client, key, value)
```

After the data transfer, verify that all data from Railz is accurately captured in Redis. Write tests to validate data integrity and consistency. Check for any errors or data mismatches and adjust your script as necessary to handle exceptions or edge cases.

```python
def validate_data(redis_client, expected_data):
for key, expected_value in expected_data.items():
actual_value = redis_client.get(key)
assert actual_value == expected_value, f"Data mismatch for {key}: {actual_value} != {expected_value}"
```

Following these steps will allow you to manually transfer data from Railz to Redis, ensuring a controlled and customized migration process without relying on third-party connectors or integrations.