# waifu2x alternative

> waifu2x is a free, MIT-licensed anime-art upscaler by nagadomi (2015); development moved to the PyTorch project nunif in 2023. Its web demo at waifu2x.net upscales 1.6× or 2× with images up to 1500 × 1500 px, and unlimited.waifu2x.net runs in your browser at up to 4×. For larger output, Kenerate AI runs Real-ESRGAN and Image Upscaler to 4K or 8K, with 25 free credits and no watermark.

URL: https://kenerateai.com/waifu2x-alternative
Publisher: Kenerate AI (https://kenerateai.com)
Last updated: 26 September 2026

## Key facts
- waifu2x.net: 1.6× or 2×, 1500 px upscale cap
- unlimited.waifu2x.net: Up to 4×, runs in your browser
- Kenerate: Real-ESRGAN, 25 MB uploads
- Kenerate max: 8K or 128 MP

## Steps
1. Open the Kenerate upscaler — Go to kenerateai.com/app/tool/image-upscale — 25 free credits on sign-up.
2. Upload your anime or manga image — JPG, PNG or WEBP up to 25 MB — no 1500 px limit.
3. Pick Real-ESRGAN or 4K — Real-ESRGAN for clean line art; Image Upscaler for an exact 4K or 8K.
4. Compare and download — Check the line art at 100% and download PNG with no watermark.

## In depth

### A 2015 classic
waifu2x was released by nagadomi in 2015 under the MIT licence. It applied the SRCNN approach — the first widely cited deep-learning super-resolution network [1] — to anime-style art, and added noise reduction for JPEG artefacts [2]. Development moved to the PyTorch project nunif in 2023 [3].

### What changed since
GAN-based models such as ESRGAN (2018) produce sharper textures than early CNNs [4], and Real-ESRGAN (2021) was trained on realistic damage — blur, noise, resizing, JPEG — with an anime-specific model [5][6]. That is why Real-ESRGAN usually keeps line art crisper at 4×, while waifu2x offers finer control over noise reduction.

### Which to use
For free 2× work on clean art, waifu2x is hard to beat. For 4× and beyond, compressed screenshots or print sizes, a Real-ESRGAN-based tool is the stronger choice.

References:
[1] Dong et al. — SRCNN (ECCV 2014 / TPAMI 2016): https://arxiv.org/abs/1501.00092
[2] waifu2x — GitHub (nagadomi, MIT): https://github.com/nagadomi/waifu2x
[3] nunif — GitHub (waifu2x successor): https://github.com/nagadomi/nunif
[4] Wang et al. — ESRGAN (ECCV Workshops 2018): https://arxiv.org/abs/1809.00219
[5] Wang et al. — Real-ESRGAN (ICCV Workshops 2021): https://arxiv.org/abs/2107.10833
[6] Real-ESRGAN — GitHub (BSD-3-Clause, anime model): https://github.com/xinntao/Real-ESRGAN

## FAQ
Q: What is the best waifu2x alternative?
A: For bigger output without installing anything, Kenerate AI: Real-ESRGAN for anime and 4K/8K output with Image Upscaler. Other options are Upscayl (free desktop app, needs a GPU) and Bigjpg (online, 20 free images a month).

Q: Is waifu2x still working?
A: Yes. The web demo moved to waifu2x.net and there is an in-browser version at unlimited.waifu2x.net. Development continues in the nunif project.

Q: Can waifu2x upscale 4×?
A: unlimited.waifu2x.net offers up to 4×; the waifu2x.net demo offers 1.6× or 2×.

Q: Is Real-ESRGAN better than waifu2x for anime?
A: Both are good at anime. Real-ESRGAN usually gives crisper lines at 4×; waifu2x gives more control over noise reduction. Try the same image in both.

Q: Can I upscale manga pages?
A: Yes. Real-ESRGAN keeps black-and-white screentone and ink lines clean; see the manga example on this page.

Q: Is Kenerate free?
A: Free to start with 25 credits on sign-up; bigger jobs use one-time credit packs that never expire. No watermark.

## Related pages
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## Sources
- waifu2x — GitHub (nagadomi): https://github.com/nagadomi/waifu2x
- nunif — GitHub: https://github.com/nagadomi/nunif
- waifu2x web demo: https://www.waifu2x.net/
- waifu2x unlimited: https://unlimited.waifu2x.net/