Visit the official NLTK Data repository and download the specific zip files you need (e.g., corpora/stopwords.zip , tokenizers/punkt.zip ).
If you are encountering a error while trying to run nltk.download() , it means your network's proxy server is blocking the connection because it requires a valid username and password. nltk download proxy authentication required
This issue is common in corporate or restricted institutional environments where internet access is strictly controlled. Here is how you can resolve it. Solution 1: Use nltk.set_proxy() Visit the official NLTK Data repository and download
If proxy authentication continues to fail due to complex security layers (like SSL inspection), the most reliable fallback is to download the data manually on a machine with open access and move it to your restricted machine. Here is how you can resolve it
If you see "SSL: CERTIFICATE_VERIFY_FAILED" after fixing the proxy, you may need to run the Install Certificates.command (on macOS) or bypass SSL verification, though the latter is less secure.
Some environments use NTLM authentication which standard Python urllib might struggle with; in those cases, using a tool like CNTLM to create a local, unauthenticated proxy is a frequent workaround for developers.
Proxy Authentication Required NLTK download - Stack Overflow