This GitHub API page provides the full reference. The API endpoint for reading a file:

https://api.github.com/repos/{username}/{repository_name}/contents/{file_path}

{
  "encoding": "base64",
  "size": 5362,
  "name": "README.md",
  "content": "encoded content ...",
  "sha": "3d21ec53a331a6f037a91c368710b99387d012c1",
  ...
}

• Consider using a personal access token
  • Rate-limits (up to 60 per-hour for anonymous, up to 5,000 per-hour for authenticated) read more
  • Enable accessing files in private repos
• The file content in the response is base64 encoded string

Using curl

Reading https://github.com/airbnb/javascript/blob/master/package.json using GitHub's API via curl:

curl -H 'Accept: application/vnd.github.v3.raw' https://api.github.com/repos/airbnb/javascript/contents/package.json

• Make sure to pass header Accept: application/vnd.github.v3.raw to get raw file response (thanks jakub.g)

Using Python

Reading https://github.com/airbnb/javascript/blob/master/package.json using GitHub's API in Python:

import base64
import json
import requests
import os


def github_read_file(username, repository_name, file_path, github_token=None):
    headers = {}
    if github_token:
        headers['Authorization'] = f"token {github_token}"
        
    url = f'https://api.github.com/repos/{username}/{repository_name}/contents/{file_path}'
    r = requests.get(url, headers=headers)
    r.raise_for_status()
    data = r.json()
    file_content = data['content']
    file_content_encoding = data.get('encoding')
    if file_content_encoding == 'base64':
        file_content = base64.b64decode(file_content).decode()

    return file_content


def main():
    github_token = os.environ['GITHUB_TOKEN']
    username = 'airbnb'
    repository_name = 'javascript'
    file_path = 'package.json'
    file_content = github_read_file(username, repository_name, file_path, github_token=github_token)
    data = json.loads(file_content)
    print(data['name'])


if __name__ == '__main__':
    main()

• Define an environment variable GITHUB_TOKEN before running

You can use the get_contents API

Here is an example:

from github import Github

github = Github('user', 'password')
user = github.get_user()
repository = user.get_repo('Demo')

file_content = repository.get_contents('sample.txt')

If you want a raw file, you just need to set request header Accept with application/vnd.github.v3.raw. Just one step would be enough.

GitHub API: /repos/{owner}/{repo}/contents/{path}

Refer to:

Official way to access / download github files from scripts?

https://docs.github.com/en/rest/repos/contents