Number 5 is the only value possible in cell (2,8).

Number 3 is the only value possible in cell (9,8).

Number 4 is the only value possible in cell (9,9).

Number 9 is the only value possible in cell (7,9).

Number 5 is the only value possible in cell (7,7).

Number 8 is the only value possible in cell (1,9).

Number 9 is the only value possible in cell (1,8).

Number 6 is the only value possible in cell (1,7).

Number 7 is the only value possible in cell (2,7).

Number 3 is the only value possible in cell (3,7).

Number 9 is the only value possible in cell (4,7).

Number 4 is the only value possible in cell (5,7).

Number 2 is the only value possible in cell (3,9).

Number 3 is the only value possible in cell (6,9).

For row 3, number 9 is only possible in cell (5,3)

For row 6, number 9 is only possible in cell (3,6)

For row 3, number 8 is only possible in cell (6,3)

For column 3, Number 8 is only possible in cell (3,5)

For row 2, number 3 is only possible in cell (8,2)

For row 5, number 3 is only possible in cell (7,5)

For row 4, number 3 is only possible in cell (4,4)

For row 4, number 4 is only possible in cell (7,4)

For row 1, number 4 is only possible in cell (1,1)

For row 2, number 4 is only possible in cell (6,2)

For row 3, number 4 is only possible in cell (8,3)

For row 3, number 7 is only possible in cell (9,3)

For box 1, candidates for 6 are all in column 3, so you can remove candidates from other blocks.

For box 3, candidates for 5 are all in column 9, so you can remove candidates from other blocks.

For blocks 2 and 8, candidates for 1 are all in the same two columns (4 and 5)

X-Wing in columns for 2.

Swordfish in rows for 1.

Either candidate for cell (3,1) forces 6 into cell (7,3).

Number 2 is the only value possible in cell (7,1).

Number 1 is the only value possible in cell (4,1).

Number 5 is the only value possible in cell (9,1).

Number 6 is the only value possible in cell (3,1).

Number 2 is the only value possible in cell (5,2).

Number 1 is the only value possible in cell (9,2).

Number 5 is the only value possible in cell (1,2).

Number 1 is the only value possible in cell (3,3).

Number 5 is the only value possible in cell (3,4).

Number 6 is the only value possible in cell (5,4).

Number 2 is the only value possible in cell (2,4).

Number 1 is the only value possible in cell (6,4).

Number 1 is the only value possible in cell (1,5).

Number 6 is the only value possible in cell (2,5).

Number 7 is the only value possible in cell (5,5).

Number 5 is the only value possible in cell (8,5).

Number 2 is the only value possible in cell (9,5).

Number 8 is the only value possible in cell (5,6).

Number 2 is the only value possible in cell (4,6).

Number 5 is the only value possible in cell (6,6).

Number 1 is the only value possible in cell (7,6).

Number 7 is the only value possible in cell (8,6).

Number 8 is the only value possible in cell (4,8).

Number 1 is the only value possible in cell (5,8).