We Built a Search Engine from Scratch - Here's What We Learned

The real challenges nobody talks about when you leave Google's shadow. The Decision Every developer has that moment. You're integrating a third-party search API, paying per request, watching costs climb, dealing with rate limits, getting irrelevant results you can't control. You think — how hard can it be to build our own? Spoiler: harder than you think. But also more rewarding than you'd imagine. This is everything we learned building a full search engine from the ground up — crawling, indexing, ranking, and serving results at scale. Phase 1: The Crawler The first challenge nobody warns you about — the web is hostile to crawlers. class WebCrawler: def init (self): self.visited = set() self.queue = deque() self.rate_limiter = RateLimiter(requests_per_second=2) async def crawl(self, url: str): if url in self.visited: return await self.rate_limiter.wait() try: response = await self.fetch(url) links = self.extract_links(response.html) self.queue.extend(links) except BlockedByRobots: pass