Kingside

Lichess vs Chess.com

Both sites play the same chess. They do not share a rating, a puzzle score, or an account.

TopicLichessChess.com
PriceFree to play, no membership required for the board, puzzles, or analysis.Free account, plus a paid membership for extra features.
AdsNo ads. The project asks for donations.Ads on the free account. Membership removes them.
SourceOpen source. The server code is public on GitHub.Proprietary service.
AnalysisStockfish in the browser, including game review on their site.Engine review, with deeper reviews on the paid plan.
PuzzlesA large set from real games, plus storm and racer drills.Puzzles and lessons, with a separate puzzle rating.
RatingsIts own pool and time controls. A number there is not a Chess.com rating.Its own pool. A number there is not a Lichess rating.
BotsBot accounts on the server, under site rules.Computer opponents on the site, under site rules.

Sources: the Lichess homepage and lichess.org, plus the public Chess.com service at chess.com. Membership details change, so check Chess.com for the current paid plan.

The short answer

Lichess is a free, libre, no-ads chess server. Its maintainers describe it that way on lichess.org, and the server code is public. Chess.com is a separate company. You can play there without paying, and a membership adds features and removes ads. Neither fact makes one site the only place to learn the rules.

If you want a game right now without an account, the board on this site plays standard chess against a local bot. It does not log you into either service.

Ratings do not convert cleanly

Each site rates the players who actually play there, in that time control. A 1500 on one site is not a published 1500 on the other. Players who keep both accounts often say their Lichess rating sits higher than their Chess.com rating, commonly by something like 100-300 points through the middle of the scale. The gap moves with the pool, the time control, and the year. Treat that range as a rumor from the player pool, not as a formula.

There is no official Lichess to Chess.com rating converter. A page that prints an exact translated number is guessing. If you need a serious figure, play 20 games on the site you care about and read that rating. Rapid, blitz, and bullet are different lists on both sites, so do not mix them.

"Is Lichess better than Chess.com" depends on the job. Lichess is the clearer choice if you want the full board, puzzles, and analysis without a paywall or ads. Chess.com is the clearer choice if you want its lessons, its content, or the specific opponents who play there. Kingside does not take a side in that product choice. It only keeps the rules of the pieces.

What to open for each job

Analysis of a single diagram: the analysis board here, or Stockfish on Lichess when the game matters. Tactics: the puzzle set here, or the Lichess puzzle database if you want thousands of positions from real games. A saved game: import the PGN.

Accounts, titles, tournaments, and reports of unfair play stay on the site where the game was played. A ban on one site is not automatically a ban on the other.

Questions

Is Lichess better than Chess.com?

Lichess is free of ads and membership fees for play, puzzles, and analysis. Chess.com offers a free account and a paid membership. Better depends on whether you want the open server or Chess.com's lessons and audience.

How do I convert a Lichess rating to Chess.com?

You do not, not officially. The pools differ. A rough player-reported gap of about 100-300 points, with Lichess higher in the middle, is only a hint. Play games on the site whose rating you want.

Do they use the same engine?

Lichess analysis uses Stockfish. Chess.com has its own engine review. The search on Kingside is a smaller local engine and is not either of those.

Keep going