you have several options here:

gnmr (google it)

inmr

mnova

--> I prefer to use Daisy in Topspin (nmrsim). We use that to fit deoxyribose spectra to extract J's

good luck

We use nuts or wxnuts

I recommend you SpinWorks 3, you can simulate and compare spectra simultaneously with the experimental. The software is free.

Also try ACD labs its free and an excellent software and its easy to learn and also comes with other packages for spetra interpretation

I agree with Cesar, SpinWorks its a great lineshape analysis tool plus it is free :-)

Hi, Dan,

if you want to analyse a multiplet you need some starting parameters (guessed or estimated coupling constants). The systematic method to extract coupling constants from first-order multiplets is described in the paper by Hoye, T. R.; Hanson, P. R.; Vyvyan, J. R.: "A practical guide to first-order multiplet analysis in H1 NMR spectroscopy", J. Org. Chem. 1994, 59, 4096-4103.

Much recommended.

Here is the abstract of the paper I just mentioned:

The ability to deduce the proper set of coupling constant (J) values from a complex first order multiplet in a H1 NMR spectrum is an extremely important asset. This is particularly valuable to the task of assigning relative configurations among two or more stereocenters in a molecule. Most books and treatises that deal with coupling constant analysis address the less useful operation of generating splitting trees to create the line pattern from a given set of J values. Presented here are general and systematic protocols for the converse, i.e., for deducing the complete set of J values from the multiplet. Two analytical methods (A, systematic analysis of line spacings, and B, construction of what can be called inverted splitting trees) are presented first. A reasonably thorough and systematic set of graphical representations of common doublet of doublets (dd's), ddd's, and dddd's are then presented. These constitute a complementary method for identification of J's through visual pattern recognition. These approaches are effective strategies for extraction of coupling constant values from even the most complex first-order multiplets.

Nowadays it is common to measure all the Js assuming a first order spectrum, which is often true with today's high magnetic fields, but not always true. Simulating a second order spectrum is more accurate, more serious and can be a lot of fun. Read this series of tutorials: http://www.inmr.net/articles/fitab.html

MestreNova ?