Contextual mobile application advertisements

A system comprising, an auxiliary content server, the auxiliary content server configured with a memory and processor to execute code, including to:

• (a) receive a keyword set from a client, the keyword set including at least one data item having a local weight computed for the data item at the client,
• (b) combine a global weight with the local weight for at least one data item of the keyword set into a final score for that item,
• (c) retrieve auxiliary content based upon the data item and score, and
• (d) return auxiliary content to the client.

One or more computer-readable storage media having executable instructions, which when executed perform steps, comprising,

• processing application page content, including extracting a plaintext keyword from the page content;
• computing a local weight for the keyword based upon local features;
• hashing the plaintext keyword into a hashed keyword;
• determining that the hashed keyword is represented in a data structure that maintains compressed data representative of advertising keywords;
• sending an advertisement request to an advertisement server, the request including a keyword set including the hashed keyword and the local weight;
• and
• receiving an advertisement from the advertisement server in response to the request.