Monitoring Hacker News for your keywords? Most "hits" don't mention them

If you track mentions of your product, framework or competitor on Hacker News, you probably use the free Algolia HN Search API. It's great: fast, free, no key. But it has a catch that is easy to miss.

The numbers

I searched HN comments since 1 October 2026 with search_by_date and then checked each result for the keyword itself:

Short words are the problem. Part of it is that Algolia also searches author names (rust returns comments by a user called rustyhancock), and it is typo-tolerant. But for deno, almost none of the extra hits contain anything that looks like "deno" at all, and I could not pin down why. Distinctive words like postgres are mostly fine.

If you count mentions, build a dashboard or feed comments into an LLM for sentiment, 85–90 % noise ruins the result.

Why the obvious fix doesn't work

My first idea was to use Algolia's _highlightResult: keep a hit if any field has matchLevel != "none". That looked perfect in a quick test, but Algolia only returns highlight data for roughly the first 70 hits of a response. Everything after that has no highlights, so this filter silently throws away most of the good results too (for postgres it kept 74 of 717 real matches). I shipped that bug for about an hour before noticing.

What works

Check the text yourself. Keep a hit only if every keyword appears at the start of a word in the title, comment text or URL:

const words = query.toLowerCase().split(/\s+/).filter(Boolean);
const res = words.map((w) => new RegExp(`(^|[^a-z0-9])${w.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')}`, 'i'));

function isRealMatch(hit) {
  const text = `${hit.title ?? ''} ${hit.story_title ?? ''} ${hit.comment_text ?? ''} ${hit.url ?? ''}`
    .replace(/<[^>]+>/g, ' ');
  return res.every((re) => re.test(text));
}

"Start of a word" keeps postgres → PostgreSQL but drops rust → trust.

Two more things you'll hit when collecting more than a few hundred items:

• The 1,000-hit cap. Algolia returns at most 1,000 results per query. With search_by_date, take the oldest created_at_i of each page and query again with numericFilters=created_at_i<{oldest} to walk back in time.
• Filtering shrinks pages. After filtering, a page of 1,000 hits might give you 80 items, so keep walking until you have enough.

Disclosure: This article was written with help from an AI assistant (Claude); the numbers come from my own queries on 18 October 2026.