LTSpice with hand calculations is not enough, so Python comes to the rescue! Link to the repository.
NOTE: This repository's author gratefully wants to thank Nuno Brum for his PyLTSpice library. Without his great work, this project would not have been possible.
The tool for finding the threshold voltage (V_th) and the transconductance (k_n) of an NMOS/PMOS. (The k_n found does not account for the Early effect, so if you want it to be more accurate, the k_n must be divided by (1 + lambda*V_ds) where lambda = 1/V_A.) Link.
The tool for finding the Early voltage (V_A) of an NMOS/PMOS. Link.
This tool evaluates the DC gain, crossover frequency, and phase margin of an op-amp open-loop gain at various input and output DC voltages with variation of supply voltage, temperature, and process corner of CMOS. Link.
This tool evaluates the power usage of an op-amp. Link.
This tool evaluates the input-referred noise of an op-amp. Link.
This tool evaluates the settling time of a closed-loop op-amp when the step input is 0.5 V. Link.
This tool evaluates the total harmonic distortion of an output wave when its swing is maximized to (V_DD - 0.2) V. The input frequency is 1 kHz, and evaluation time is 10 ms. Link.