Strobe Tuner is the one of the most accurate tuner. A strobe tuner shows the difference between a reference frequency and the musical note. Even the slightest difference between the two will show up as a rotating motion in the strobe display. The accuracy of the tuner is only limited by the internal frequency generator. (Just refer to the link for more about Strobe Tuner)
Though we do not have the strobe hardware, insTuner supports to simulate the strobe display to make your tuning even more accurate.
The bars  scroll to the left when the note is too flat and to the right when the note is too sharp. The movement speed of the bar indicates the value of the error cent. When the note is in tune, the bars remain still.
Take the image above for example.
 As shows above, the current detected frequency is 233.7 Hz.
 The error between the frequency and Bb3 is 4.6 Cents. You can refer to the link for more details of Cent.
 On the right side of the screen, we can see that “A4 = 440Hz”. Concert A, aka. A4 or A440, which has a frequency of 440 Hz, is the musical note A above middle C and serves as the general tuning standard for musical pitch. You can refer to Wikipedia for more about A4.
 Trans = C: It shows the Current Transposition. The transposition function is very useful for transposing instruments like French Horn (F Key) and Saxophone (Bb Key). The default key without transposition is set to C.
 12TET: Current Temperament Settings. In musical tuning, a temperament is a system of tuning which slightly compromises the pure intervals of just intonation in order to meet other requirements of the system. Most instruments in modern Western music are tuned in the equal temperament system.
The most common tuning system is 12 Tone Equal Temperament, aka. 12TET, which divides the octave into 12 parts, all of which are equal to a logarithmic scale. It is usually tuned based on the standard pitch of 440 Hz, called A440. Refer to the following link for more about Musical Temperament.