We report on an all-fiber femtosecond Ytterbium laser without dispersion compensation operating in the similariton pulse regime. The oscillator was mode-locked with a saturable Bragg reflector along with nonlinear polarization evolution. A pulse energy of 0.8 nJ was achieved with a pulse duration of 10 ps. The pulses could be externally dechirped to 627fs which was within 8.7\% of the Fourier transform limited pulse duration. The realized oscillator combines compact size, high stability and alignment-free operation.