Yes, but Elasticsearch requires a dedicated server, you may have to use a river, you may have to shard, etc. Some people (most people?) don't want to think about shards & rivers and just want something to work. Algolia seems to do that.

I know what a shard is, but what's a river? I've never heard anyone use that term in a technical context before.

I used ES a long time ago and rivers have since been deprecated: https://www.elastic.co/blog/deprecating-rivers

A river was just a mapping from a database to ES. For example, you could search CouchDB with ES with the proper river set up.

In Elasticsearch a "river" is the description for the pushing of data from your primary store (A database more than likely) into the elasticsearch index.

ES actually started with Rivers being part of Elastic but since deprecated it. You will still find people talking about "rivers" though as a description for however they are updating the index.

there are lots of things like this. it's bizarre that i pay for email when there are good and free email services (and my privacy/security needs are pretty damn simple.) people don't mind paying for things they like, or for something that provides just a little detail that others do not.

Algolia provides things that elasticsearch do not, such as being hosted, being extremely simple to setup and having a default web interface for anyone to use.

There are plenty of companies providing hosted ElasticSearch these days, starting with Elastic.co, the corporate sponsors of the open-source project. Amazon hosted ES is also a lot better than it was just a few months ago; they were stuck on 1.5 for the longest time, but now they've already got support for 5.1.1.

The database is just a building block for the search. You still have to implement a lot of logic and smartness on top.

algolia does that out of the box.

It's not that hard though. I'm a junior dev and i managed to implement ES ( AWS hosted of course) for our site search on my on own. If i can do it, pretty sure majority of people can do it.

nothing like this is hard. being Junior or not has nothing to do with it. it's a question of investing time/money

I'll give you free, but I'm not sure about good. For the www site I run, we have run a one node instance on each machine; they regularly decide to go off into the weeds and not return results, and in the meantime use ridiculous amounts of ram.

I wish Yahoo would have open sourced some of it's internal search tools. :( They weren't always simple to use, but they were stable.