HippoRAG / HippoRAG2
https://github.com/OSU-NLP-Group/HippoRAG
Hippocampus-inspired RAG. LLMs + knowledge graphs + Personalized PageRank to mimic neocortex/hippocampus roles. NeurIPS 2024.
Active · Verified 2026-10-23 · fresh as of 2026-10-23 · 32 cited facts, 1 with a third-party source · 1 recorded change · Suggest a correction
At a glance
- Type
- Personalised PageRank over KG repo fix
- Tier
- T3
- Section
- Retrieval-as-memory hybrids
- Latest release
- v2.0.0a4 (2025-06-24) — PyPI pre-release; last GitHub release v1.0.0 (2025-02-27) registry fix
- GitHub
- OSU-NLP-Group/HippoRAG — ~4.0k stars repo fix
- Pricing
- searched not found fix
- Funding
- not applicable — not commercial fix
- Freshness
- 2026-10-23 fix
- Layer
- agent-infra repo fix
- Licensing
- open-source repo fix
- Protocols
- mcp-server repo fix
- Developer activity
- OpenRank 0.46 (12-mo avg 2.38) · 2 participants — 2026-09 third-party fix
Memory taxonomy
- storage
- graph
- retrieval
- graph-traversal
- persistence
- long-term
- update
- read-only
- unit
- chunk
- governance
- inspectable
- conflict
- n/a
When to use
Optimised for: retrieval quality / accuracy on long-context QA
Anti-fit: most are research papers; production fitness varies by maintainer
Pros & cons
Pros
Hippocampus-inspired single-pass retrieval — strong on multi-hop questions where multi-pass retrieval struggles.
Cons
Index build cost is high; eval primarily on synthetic multi-hop tasks.
Claims & capabilities
Up to +20% on multi-hop QA over SOTA. Single-step retrieval ≥ iterative IRCoT at 10–30× lower cost and 6–13× faster. v2 (Feb 2025) outperforms GraphRAG / RAPTOR / LightRAG.
Technical surface
- API surface
- not applicable — research paper
- Backend storage
- not applicable — research paper
- Deployment
- searched not found
- Embedding model
- not applicable — research paper
- Multi-tenancy
- not applicable — research paper
- MCP
- not applicable — research paper, no deployed product
- A2A
- not applicable — research paper, no deployed product
- OpenTelemetry
- not applicable — research paper, no deployed product
Alternatives to HippoRAG / HippoRAG2 → live options ranked by shared design, licence, hosting and MCP support
Similar systems
Other retrieval-as-memory hybrids in the catalog, ranked by inbound references.
- GraphRAG (Microsoft) T1
Modular graph-based RAG. Leiden community detection over knowledge graph; community summaries at multiple levels. DRIFT Search hybrid (Oct 2024). The GraphRAG repo is now largely in maintenance mode: no new features or PRs, only bug fixes and dependency/CVE updates.
- RETRO T3
DeepMind. Retrieval-Enhanced Transformer with chunked cross-attention over a 2T-token retrieval database. Frozen BERT retriever + differentiable encoder.
- Atlas T3
Meta AI. Jointly fine-tunes retriever + LM for few-shot tasks. The facebookresearch/atlas repo is no longer maintained; the code is provided as is.
- RAPTOR T3
Stanford recursive-summarisation tree over the corpus — clusters and summarises documents into a hierarchical index; retrieves at multiple levels. ICLR 2024.
- Self-RAG T4
Trains an LLM end-to-end to emit reflection tokens that decide whether to retrieve, assess passage relevance, and critique output quality — all within a single model.
- MemoRAG T4
RAG variant with a long-context global memory model that drafts answer clues used to guide passage retrieval — improves recall in noisy multi-hop QA.
Sources (31 cited facts, 1 third-party)
Each fact links to the page it came from; the badge says who published it (how to read sources).
- What it is Personalised PageRank over KG repo
- What it does & what's distinct Hippocampus-inspired RAG. LLMs + knowledge graphs + Personalized PageRank to mimic neoco… repo
- Claims / benefits Up to +20% on multi-hop QA over SOTA. Single-step retrieval ≥ iterative IRCoT at 10–30× … repo
- Created 2024-05 repo
- Latest release v2.0.0a4 (2025-06-24) — PyPI pre-release; last GitHub release v1.0.0 (2025-02-27) registry
- License MIT repo
- GitHub OSU-NLP-Group/HippoRAG — ~4.0k stars repo
- Citations 103 cites 51/yr paper
- Founders / pedigree Ohio State University NLP Group (OSU-NLP); Bernal Jiménez Gutiérrez, Yiheng Shu, Yu Gu, … repo
- Reproducibility Independently reproduced paper
- Code/weights release Code public + weights closed repo
- Versioning none repo
- Schema evolution schema with migration repo
- Validated verticals research, RAG developers (horizontal); some have production deployments repo
- Anti-fit most are research papers; production fitness varies by maintainer repo
- Optimised for retrieval quality / accuracy on long-context QA repo
- Adjacent infrastructure BYO LLM + vector store; OSS reference implementations exist repo
- Pros Hippocampus-inspired single-pass retrieval — strong on multi-hop questions where multi-p… repo
- Cons Index build cost is high; eval primarily on synthetic multi-hop tasks. repo
- Project & sources GitHub OSU-NLP-Group/HippoRAG arxiv 2405.14831 NeurIPS 2024 PDF repo
- commit-trajectory [{"ym":"2024-05","cum":13},{"ym":"2024-06","cum":63},{"ym":"2024-07","cum":83},{"ym":"20… repo
- citation-trajectory [{"year":2024,"cum":3,"infl":1},{"year":2025,"cum":10,"infl":3}] paper
- download-trajectory [{"ym":"2025-11","monthly":652,"cum":652},{"ym":"2025-12","monthly":1415,"cum":2067},{"y… registry
- architecture-deployment-locus local repo
- licensing-bucket open-source repo
- positioning-platform-vs-product platform repo
- taxonomy-three-layer-rollup agent-infra repo
- developer-activity-opendigger {"activity":3.04,"as_of":"2026-09","openrank_12mo":2.38,"openrank_current":0.46,"partici… third-party
- sdk-languages python repo
- protocol-support mcp-server repo
- maturity alpha registry
What changed
Changes to this record's lifecycle, licence, release, pricing and hosting facts, from the catalog's git history. Subscribe (Atom)
Related systems
Referenced by (3)
- CAM cites — S2 isInfluential citation
- From Human Memory to AI Memory (survey) cites — S2 isInfluential citation
- KAG cites — S2 isInfluential citation