This is mostly some feedback ( not sure if it counts as negative or positive 
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about my Qspice experience (most are LTspice related)Some might not be a problem if someone uses Qspice a lot but use it semi regularly :
1 Voltage sources dont have a GUI pop up that LTSpice has. It is the same syntax and often i type in LTSpice since there it is easier to write since you can see what parameter you change.
2 Same for current sources and other things that had a GUI.
3 Reopen Waveform viewer is a bit hidden. In LTspice is one of the most used buttons for me same in Qspice. My suggestion is to make it a icon on the top bar.
4 Didn’t test this yet in Qspice but in LTSpice there are things that aren’t as multi thread as they can be: when doing a parameter sweep you could run them all in parallel but they are run sequentially maybe Qspice could be better here tho best way would be to have some settings since RAM usage may e a problem.
These are a few ideas of what i would improve in Qspice and i am posting here so others can also judge and or agree or say otherwise.
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Currently, if you close the waveform viewer after the simulation is run in Qspice, you can reopen it with View > Reopen Waveform Viewer, a two-click operation in Qspice compared to a one-click icon in LTspice. (possibly we can ask for a shortcut). But I have a question about this: unlike LTspice, the Qspice waveform viewer is a separate window, so you don’t have to close the waveform viewer to edit the schematic; you can simply switch between windows by a mouse click. Why do you have to close the waveform viewer and reopen it later (where without running another simulation)?
Do you mean .step runs in parallel in LTspice? My understanding is that .step is always sequential in SPICE. For example, set up this example and you can clearly see waveforms displayed one by one during the simulation. Do you mean there is an option in LTspice to run .step simulations in parallel, providing an advantage in overall simulation time?
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Yes, this is a very interesting discussion. SPICE is a netlist-based simulator, where everything actually runs in the netlist. A device can have a huge number of instance parameters to set it up. The pop-up menu can be a disadvantage for advanced users but friendly to infrequent users. Mike set up a standard with his LTspice, but he disliked it and redesigned it with Qspice. However, many LTspice users may disagree with that. (I also come from LTspice. I didn’t like it at the beginning, but eventually, I found it too convenient and disliked going back to the old way).
For example, if you paste .step param x 1 10 1 param y 1 10 1 as a directive in LTspice and then right-click for the pop-up window, the GUI will not mention anything about the second part of this .step. However, this syntax is actually valid in SPICE.
You frequently see updates in Qspice, and new instance parameters can be made available at any time. The approach of “Add Attribute” as instance parameters could make things easier when new features are delivered. It is also visible in schematic level how you setup a device. Unlike LTspice, you can simply don’t know what Rser is actually set for a capacitor from its schematic. It is quite clear that in multiple videos and discussions, Mike has expressed that he intentionally removed the pop-up menu. For advanced users, we see the disadvantages of the pop-up menu, but this may not be as clear for infrequent users.
However, infrequent users make up the majority. In my personal opinion, a custom symbol that looks like Advanced Design System (ADS) or QUCS could be beneficial. This is the closest thing I can think of to having more visual and easy-to-set-up symbols within the current Qspice infrastructure.
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In the symbol of the inductance L2 Q=100, you should add FREQUENCY=. After all, the quality factor Q changes with a change in frequency.
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I made that one with frequency invisible, as I considered that QUCS with this symbol and default freq by 100MHz.
But I think I will have another one with frequency visible.
Why ? because mistakes happen and also this is the fastest way to remove all plots and reset all scales. Might just be me and a few colleagues.
Yes from what i remember max core count setting in LTspice was 4 cores. And i am not sure if there is a hardcoded limit in Qspice or not or it can use all cores , from what i saw this does not seem to be the case. As for the command i was thinking of sweep but step is also a good case. Since you say it is a SPICE limit then i am not sure if it can be improved. At work i often split long step simulations in discrete ones and started them in parallel instances of LTspice and that was overall faster since i could use my entire I7 CPU. We are talking about 30-40 min per instance here min maxing CPU was sort of needed. Yea it was hard to keep track of all changes but it was way faster.
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Or have a GUI by default and have a settings menu where u can disable it. As for the user base.. i mostly do digital but sort of often i need to redesign some analog audio and then i do a ton of SPICE then nearly noting for a few months.
Alternatively it can be made more clear on the right side parameter menu.
For the Reopen Waveform feature, I suggest discussing with Mike if a shortcut key can be added.
Regarding multi-threading, I realize that I misunderstood your suggestions; it’s very interesting, but have no knowledge in this area.
In terms of GUI, I believe it would be best to involve @mccunets for a long-term review, how Qspice GUI can help newbies, infrequent users, and users of other SPICE platforms work more easily. This has been a topic repeatedly raised by the community. From my perspective, I think Qspice interface actually helps SPICE users understand the true nature of SPICE. Anyone who is skilled in SPICE requires to master the netlist syntax, and the pop-up GUI is friendly to newbies but may mask this important aspect. But it’s true that many users are not aiming to master SPICE but simply to use it.
One more thing, Qspice is developed solely by Mike, making it a one-man job. A clear GUI enables more features, fewer bugs, and quicker delivery of new features and functions.
In the end, what we need is to complete the simulation job, and to be fair, many professional software programs require time to master. I started with Pspice, which is full of icons and graphics, but if someone asked me to build a circuit from a blank schematic now, I would have a hard time. For those who have worked on LTspice for many years, I fully understand why they may find Qspice challenging (I had this experience 3 years ago). To be honest, if not a unique feature of Qspice attract you and you truly need that in your circuit simulation, perhaps there’s no need to switch. For me, Qspice offers multiple features that do not exist in other SPICE platforms, making it worth the time (e.g. C++ DLL-device, superior digital domain simulation, S-parameters and SmithChart, .s2p support). For new beginners in SPICE, I definitely suggest starting with Qspice.
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Well i dont know the username of Mike so i cant send this to him.
There are ICs that have a very poorly optimized model that take ages to simulate i just emulated parallelism ( it was SMPS controll ICs from ADI and TI).
I dont know what dev work is required for GUI i am only a user in this area.
As for me i am migrating here and there since i can use Verilig for digital blocks ( corporate antivirus does not like that i generate .DLL so C tho preferable for me is not usable). As of now i am like useing both here and there based on what i have to start and what i need.
Since i use SPICE oance a few months but when i use it it is intense, i cant say i am a noob or a pro. But also i want to avoid useing another Spice like TINA or TI Pspice.
BTW regarding parallelism maybe Qspice can run some virtual instances in parallel then merge them at the end or as they are ready in chunks.
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Update Qspice and Shortcut F8 is assigned for Reopen Waveform Viewer
02/02/2026 F8 can now be used to reopen the waveform viewer.
I think Mike Engelhardt is no longer active in the forum, but you can reach him through his official email, which is mentioned in Qspice > Help > About. The forum is now primarily for crowd support, but bugs should be reported through email. Qspice is actively evolving, and what is currently missing may become available a few months later. Sometimes it can take longer; for example, .net network parameters were finally introduced in Jan-2026, after Qspice had been launched for 2.5 years. But I guess the pop-up menu may never be implemented, as it goes against the idea that Mike intended what he want in Qspice.
NICE.
I didnt think i would suggest something that well and implemented that fast WOW.
Yea pop up may not be the what way to go with Mikes vision tho i can think of another way or someone else with more UI ideas can.
Nice suggestions. I totally agree with 1/2 since it it more tedious then LTspice. And yea i also do that LTspice to Qspice copy paste.
Since Mike is against pop up maybe something more explicit on the right hand menu (Symbol properties) maybe string attribute is a bit more verbose after you type first attribute? Like after you type SINE there are extra lines that are like in the old LTspice pop up. Just a suggestion.
As for 4 i had no problems yet in Qspice but in LTspice LM5046 took AGES to simulate like 40-50min at like 1us/s.
3 is nice to have
Hmm good idea. Also man that is long simulation time or something not converging well in the IC you mentioned.
Since we are on the topic of suggestions maybe a built in array or classic jellybean parts?
There are the Quorvo parts and some onsemi parts, i was thinking more like standard 74 logic chips that are generic and or diodes mosfets so you dont have to search for generic models.
I’m not sure why, but if we follow the path of LTspice, many generic parts are built by the community.
An active contributor in the forum has also engaged in a discussion with me about whether the community can collaborate to centralize symbol libraries for generic parts. Currently, it appears to be quite challenging, but we are hopeful that as more dedicated individuals join the Qspice community in future, such collaborative efforts will become feasible.
I have begun constructing the 7400 series (Ideal parts without added propagation delay yet) and have consolidated various public diode, MOSFET, BJT, and JFET libraries into a unified one. Since Qspice supports copy and paste to automatically generate symbols from the .model statement, you can simply search for the device in the library, copy the .model statement, and paste it into Qspice to convert it into a device.
Qspice/Symbols-KSKelvin/digital/7400 series · KSKelvin-Github/Qspice
Qspice/SPICE-Library · KSKelvin-Github/Qspice
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NICE.
Here is another idea:
Add Wav file support like it was in LTspice. it is a simple file type and besides the header it is raw data and should be not that hard to code. As opposed to MP3. Often when i deal with audio can cant figure out if this DC shift will make it sounds off or not.
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