FORTUNE — Quora, the online Q&A platform launched five years ago by a pair of former Facebook FB execs, today announced that it has raised $80 million in its third round of venture capital funding. The Mountain View, Calif.-based company isn’t disclosing the round’s valuation, but a source familiar with the situation pegs it at around $900 million.

Tiger Global led the deal, and was joined by existing shareholders like Benchmark, Matrix Partners and North Bridge Venture Partners.

Quora basically views itself as a complement to Wikipedia, in terms of both mission (growing and sharing the world’s knowledge base) and quality control (no traffic-boosting memes, cat photos, etc.). And, in that vein, it has no interest in ever being acquired.

“I don’t think you could achieve what we’re trying to achieve without being independent,” explains Marc Bodnick, Quora’s head of business and community. “Keeping quality at a massive scale is not easy to do, and I think it would be impossible if we were owned by someone else.”

That effectively means that Quora intends to go public at some point, but don’t expect registration documents any time soon. For starters, Quora has never generated a dime in revenue. Never even tried. The company plans to flip the monetization switch at some point next year, although Bodnick declined to provide more specific timing.

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Second, Quora doesn’t really need the money. It has an extremely low burn rate, due in part to its lack of marketing or customer acquisition costs. In fact, it still has most of its $50 million Series B round (from May 2012) in the bank (despite having around 70 employees). Bodnick says that the company wasn’t actually looking to raise its Series C round yet, but acquiesced after being approached by Tiger. “This round lets us keep money in the bank as insurance,” he adds.

The round also should help Quora to continue scaling up its service, including plans to have its library available in all major world languages (currently it’s only in English).

Bodnick acknowledges outside perception that his company has largely plateaued in terms of user growth, with just a small band of core contributors, but argues that such sentiments are misleading. “For starters, we think the major audience analytic services you’re referencing are off by between a factor of 5x and 15x,” he says. “But, more importantly, we’re experiencing strong growth across all metrics — usage, library size, etc. We have over 500,000 topics on the site and, if you’re an active writer, you can attract between 10 million and 15 million annual views on your content. Our intent is to keep building that size as a single offering, executing on the mission.”

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