kitio.aiFaiss vs OpenNN
A side-by-side look at pricing plans, free tiers, features, pros and cons, updated for 2026. Faiss starts at Free and OpenNN starts at Free. Check both pricing pages for current plans.
At a glance
Best for
Category
Pricing model
Starting price
Free plan
Made by
Based in
Rating
Key features
- Nearest neighbor search
- Clustering
- GPU algorithms
- Python wrappers
- Indexes larger than RAM
- Evaluation tools
- Dense, LSTM and CNN networks
- Transformers
- CPU and CUDA GPU training
- Tutorials and benchmarks
| Feature | Faiss | OpenNN |
|---|---|---|
| Best for | Open-source library for similarity search over dense vectors | Open-source C++ library for building neural networks |
| Category | Models & APIs | Models & APIs |
| Pricing model | Free | Free |
| Starting price | Free | Free |
| Free plan | Yes, fully free | Yes, fully free |
| Made by | Meta FAIR | Artelnics |
| Based in | United States | Spain |
| Rating | No ratings yet | No ratings yet |
| Key features |
|
|
Pricing compared
Faiss starts at Free and OpenNN starts at Free. Check both pricing pages for current plans.
Free plan
Cheapest paid plan
Top plan
Free trial
Prices in USD, checked Oct 29, 2026 or later. Plans change often, so confirm on each tool's site before you buy.
Pros and cons
Faiss
- Free and open source
- Scales past available memory
- GPU support for key algorithms
- A library, not a managed service
- Needs engineering effort to deploy
- Not a database, so no built-in server or storage
OpenNN
- High-performance C++
- Runs on CPU or GPU
- Covers several network types
- Requires C++ skills
- Smaller ecosystem than Python libraries
- Licensing page may apply to commercial use
Which one should you choose?
Choose Faiss if you want:
- Free and open source
- Scales past available memory
- GPU support for key algorithms
Watch out: a library, not a managed service.
Choose OpenNN if you want:
- High-performance C++
- Runs on CPU or GPU
- Covers several network types
Watch out: requires c++ skills.
Faiss vs OpenNN FAQ
What is the difference between Faiss and OpenNN?
Faiss: Open-source library for similarity search over dense vectors. OpenNN: Open-source C++ library for building neural networks. Both are models & apis tools.
Is Faiss or OpenNN cheaper?
Faiss starts at Free and OpenNN starts at Free. Check both pricing pages for current plans.
Do Faiss and OpenNN have free plans?
Faiss: Yes, fully free. OpenNN: Yes, fully free.
Who makes Faiss?
Faiss is made by Meta FAIR, based in United States.
Who makes OpenNN?
OpenNN is made by Artelnics, based in Spain.
Which should I choose, Faiss or OpenNN?
Choose Faiss if you value free and open source and scales past available memory. Choose OpenNN if you value high-performance c++ and runs on cpu or gpu.