Chess FEN Viewer

How to use

1. 1Paste a FEN string into the input, or pick a preset to load the starting position, a famous game, or a worked example.
2. 2Read the board: rank 8 is at the top by default. Click Flip board to view from black's side, or toggle coordinates to show or hide file letters and rank numbers.
3. 3Check the decoded fields panel for side to move, castling rights, en passant target, halfmove clock, fullmove number, and the centipawn material balance.
4. 4Read the validation panel for any errors and warnings, including illegal placement characters, wrong file counts per rank, repeated castling flags, en passant targets on the wrong rank, and castling rights that do not match the kings and rooks on the board.
5. 5Click Copy normalized FEN to grab the canonical form, which re-encodes the placement with minimal run-length empties and supplies defaults for any missing halfmove or fullmove fields.

About this tool

Chess FEN Viewer parses any Forsyth-Edwards Notation string and renders the position as a board in your browser. FEN is the universal text format for chess positions: it packs the entire game state into six space-separated fields. The first field is the piece placement, written rank 8 down to rank 1 with files a through h. Upper-case letters (K, Q, R, B, N, P) are white pieces, lower-case letters (k, q, r, b, n, p) are black, and digits 1 through 8 represent runs of empty squares. The remaining five fields describe whose turn it is (w or b), the castling rights still available (a subset of KQkq, or - for none), the en passant target square if a pawn just advanced two squares, the halfmove clock used to count plies toward the 50-move rule, and the fullmove number that increments after every black move. The tool validates each field independently and surfaces real engine-rejecting problems: the wrong number of files in a rank, an illegal character in the placement, a side-to-move other than w or b, repeated castling flags, an en passant target on the wrong rank for the side to move, a halfmove clock that has crossed the 50-move threshold, more than one king of a single color, pawns parked on the 1st or 8th rank, and castling rights that name a king or rook that is not actually on its home square. Loose four-field copies from Lichess study links or chess.com analysis URLs are accepted: the tool fills in 0 1 for the missing halfmove and fullmove numbers and flags the missing fields as warnings. The decoded panel shows side to move, expanded castling rights, en passant target, both move counters, a centipawn material balance, and per-color counts of every piece. The board renders with Unicode chess glyphs so it works on any device without an external font or image. Flip the board to view from black's side, toggle the file and rank coordinates, and copy a canonical normalized FEN that re-encodes the placement using minimal run-length empties. Useful for chess developers building engines, bots, opening trees, or analysis tools; for streamers and writers who paste FEN strings into articles and want to preview the result; and for players who want to inspect a position quickly without opening a board editor. All parsing, validation, and rendering run locally in your browser; the FEN strings you paste are never uploaded.

Free to use. Works in your browser. No signup, no login.