Whole-corpus specialist
Microsoft global search uses community reports in a map-reduce query. It is distinctive—and resource intensive.
Project Atlas · Technical Landscape
A README-based comparison of eight shortlisted open-source graph knowledge systems, complemented by Stripe and Cerebras production reference architectures.
Matrix 01
Projects that share the “GraphRAG” label solve substantially different problems. This is the most important matrix in the report.
| Shortlist | Designed to do | Best fit | Not primarily |
|---|---|---|---|
| nano-graphrag | Small implementation of Microsoft-style GraphRAG | Learning, source study and controlled experiments | A complete multi-tenant production platform |
| Microsoft GraphRAG | Batch extraction, graph communities and hierarchical reports over documents | Whole-corpus themes plus entity-focused questions | A supported managed product or native graph database |
| LightRAG | Lighter graph/vector RAG server with several retrieval modes and storage adapters | General self-hosted GraphRAG, incremental documents and multimodal files | A formal ontology or symbolic-rule engine |
| HippoRAG | Long-term memory retrieval using a KG and Personalized PageRank | Associative, multi-hop and continual-learning research | A turnkey enterprise knowledge platform |
| Graphiti | Bi-temporal context graph that evolves episode by episode | Agent memory, changing facts and historical questions | Static whole-corpus community summarization |
| KAG + OpenSPG | Schema-constrained domain knowledge plus logical-form-guided reasoning | Professional domains with rules, terminology and factual multi-hop questions | A minimal plug-and-play RAG library |
| Neo4j GraphRAG + Graph Builder | Practical KG construction and multiple retrieval patterns on Neo4j | Property-graph applications, Cypher and managed graph infrastructure | Database-neutral GraphRAG |
| TrustGraph | Full context-engineering and agent backend using ontology, graph/vector retrieval and provenance | Sovereign, explainable, multi-tenant context infrastructure | A small embeddable library |
Matrix 02
| Capability | nano | Microsoft | LightRAG | HippoRAG | Graphiti | KAG / OpenSPG | Neo4j | TrustGraph |
|---|---|---|---|---|---|---|---|---|
| Automatic entity/relation extraction | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Formal schema/ontology | — | ◐ | ◐ | — | ✓ | ✓ | ✓ | ✓ |
| Vector + graph retrieval | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| Lexical/keyword retrieval | — | — | ◐ | ◐ | ✓ BM25 | ✓ exact/text | ✓ full-text | ◐ |
| Whole-corpus global summary | ✓ top communities | ✓ map-reduce reports | ✓ global/mix | — | — | — | ◐ global-vector | — |
| Incremental ingestion | ✓ report rebuild | ◐ batch-biased | ✓ | ✓ continual | ✓ real-time episodes | ✓ iterative | ◐ pipeline-driven | ✓ flows |
| Selective deletion/retraction | ◐ | ◐ | ✓ affected-KG rebuild | ◐ | ✓ temporal invalidation | ◐ | ◐ app logic | ◐ version/flow |
| Explicit temporal validity/history | — | — | — | — | ✓ bi-temporal | — | — | ◐ freshness/version |
| Symbolic rules/logical reasoning | — | — | — | — | — | ✓ KGDSL/reasoner | ◐ Cypher traversal | ◐ ontology policy |
| Multi-hop/associative retrieval | ◐ | ◐ DRIFT/local | ◐ relationship chains | ✓ PPR | ✓ graph search | ✓ | ✓ graph/Cypher | ✓ traceable paths |
| Multimodal document reasoning | — | — | ✓ VLM + parsers | — | — | ◐ processing | ◐ varied sources | ◐ media stack |
| Built-in web UI | — | — | ✓ | — | — core | ◐ | ✓ Graph Builder | ✓ |
| REST API / MCP | Library | CLI/Python | ✓ REST | Library | ✓ REST/MCP | SDK/server | Python + app API | ✓ API/MCP |
| Built-in multi-tenancy/isolation | — | — | ◐ workspaces/auth | — | ◐ groups | ◐ project/domain | App/database dependent | ✓ workspace/collection/flow |
Microsoft global search uses community reports in a map-reduce query. It is distinctive—and resource intensive.
Graphiti uniquely models fact-validity windows and preserves superseded facts as history.
KAG/OpenSPG provides the strongest schema, normalization and rule model, with the highest up-front modeling work.
TrustGraph supplies orchestration, storage, ingestion, retrieval, MCP and UI—along with the largest operations surface.
Matrix 03
| Shortlist | Storage | Model choices | Deployment | Main operational concern |
|---|---|---|---|---|
| nano | Disk KV, nano-vectordb, NetworkX; Neo4j/HNSW/Milvus/FAISS options | OpenAI, Bedrock; examples for Ollama, DeepSeek and sentence-transformers | Python package, single host by default | Incremental inserts avoid duplicate chunks but recompute communities and reports |
| Microsoft | Parquet tables plus configured vector store; no graph DB required | Configurable model providers and LiteLLM | CLI or Python index/query pipelines | Many standard-index LLM passes; version/config changes can require migration or re-indexing |
| LightRAG | KV, vector, graph and document-status roles; unified or specialized production backends | Separate extraction, query, keyword and VLM roles; hosted or local providers | REST server/Web UI via Docker, or Python core | Storage tuning; embedding-dimension changes require vector-state rebuilding |
| HippoRAG | Local output/index artifacts in packaged workflow | OpenAI-compatible, Bedrock and local vLLM | Python research/library workflow | GPU/model capacity and independent validation of research results |
| Graphiti | Neo4j, FalkorDB or Neptune; Neptune also uses OpenSearch Serverless | OpenAI default; Anthropic, Gemini, Groq and compatible/local servers | Python core, FastAPI and MCP | Structured-output reliability, graph operations and ongoing extraction/deduplication |
| KAG/OpenSPG | OpenSPG engine with pluggable graph and algorithm services | LLMs plus NLP/deep-learning operators | Engine, builder, reasoner, SDK/server and domain solution | Schema governance, entity alignment, custom operators and integration complexity |
| Neo4j | Neo4j 5.x + APOC; vectors in Neo4j or external Weaviate/Pinecone/Qdrant | Ollama, OpenAI/Azure, Google, Cohere, Anthropic, Mistral and Bedrock | Python package, Graph Builder UI/backend, self-managed or Aura | Neo4j capacity and production caution around experimental KG-builder APIs |
| TrustGraph | Cassandra, Qdrant, Garage object storage and Pulsar or RabbitMQ | Hosted providers or local vLLM, Ollama, TGI, LM Studio and Llamafiles | Multi-container Docker/Podman or Kubernetes | Largest platform-operations footprint, though fewer mandatory external services |
Matrix 04
Stripe and Cerebras demonstrate production patterns, but neither publishes a reusable end-to-end knowledge-base implementation. They are references, not additional open-source shortlist candidates.
| Reference | Scope and interface | Retrieval and storage | Graph / Tree-sitter | Security | Openness and price | Atlas lesson |
|---|---|---|---|---|---|---|
| Stripe AI knowledge base | Hosted MCP for searching Stripe documentation and support material, alongside narrowly scoped API discovery, planning, read and write tools | Backend retrieval, ranking and storage are not publicly disclosed | No public evidence of a knowledge graph or Tree-sitter | OAuth or restricted API keys, account scope, constrained tools and confirmation for consequential actions | Client and agent tooling is MIT; hosted KB backend is proprietary. No separate public KB/MCP list price found. | Expose knowledge and actions as safe, task-oriented tools—not storage or a generally privileged agent |
| Cerebras Knowledge | Internal enterprise knowledge across Slack, code, documents and operational systems, delivered through web, automation and simple MCP retrieval primitives | PostgreSQL text, embeddings and metadata; full-text/vector retrieval with source signals, freshness, rank fusion, reranking and context restoration | Not GraphRAG. Cerebras names CocoIndex; current CocoIndex code indexing uses Tree-sitter, making this an indirect connection rather than proof of Cerebras's exact deployed splitter version. | Authentication, authorization, auditing, analytics and project/source scoping; exact row-level ACL mechanics are not public | Internal system with no public price; individual infrastructure components are independently available | Build an ACL-aware hybrid baseline first; add graphs only for measured multi-hop, temporal or ontology gains |
Narrow MCP tools, scoped credentials and human confirmation establish a strong boundary around knowledge and actions.
Incremental ingestion, source-specific processing, hybrid ranking and evidence packaging create a strong non-graph baseline.
Tree-sitter preserves code structure before embedding or graph extraction; it is an ingestion technique, not a graph engine.
Matrix 05
Relative cost is an architectural judgment, not an equal-corpus price benchmark. A fair comparison fixes corpus, model quality, schema, update rate, query mix, latency SLO and evaluation target.
| Shortlist | Repository | Managed option | Public list price | Self-hosted cost drivers | Cost tendency |
|---|---|---|---|---|---|
| nano | MIT · $0 | None published | Not applicable | Extraction/summary models, embeddings, optional graph/vector DB | Low lab infrastructure; medium–high indexing tokens |
| Microsoft | MIT · $0 | Repository is not an officially supported offering | No GraphRAG product price | LLM extraction and summaries, community reports, query model, embeddings, vector storage | High standard indexing/global search; FastGraphRAG is cheaper |
| LightRAG | MIT · $0 | None published | Not applicable | Four storage roles, four model roles, embeddings, reranker and parsers | Medium with local models; rises with multimodal/production backends |
| HippoRAG | MIT · $0 | None published | Not applicable | LLM/embedding APIs or GPU-hosted vLLM, index storage | Low–medium offline per README; verify independently |
| Graphiti | Apache-2.0 · $0 self-hosted | Zep | Free: 10k credits/month. Flex: $125/month or $1,250/year. Flex Plus: $375/month or $3,750/year. Enterprise: negotiated. | Models, embeddings/reranker, graph DB and continuous episode processing | Medium–high self-hosted; managed scales with episode bytes |
| KAG/OpenSPG | Apache-2.0 · $0 | No public managed price found | Not published | Graph engine, compute, LLMs, NLP operators, modeling team and operations | High engineering/fixed cost |
| Neo4j | GraphRAG/Builder · $0 | AuraDB | Free: $0. Professional: $65/GB/month; 1 GB example $65.70/month. Business Critical: $146/GB/month, 2 GB minimum; 2 GB example $292/month. | Database capacity, extraction/generation, embeddings, app compute, optional vector DB | Low prototype cost; predictable DB + variable models |
| TrustGraph | Apache-2.0 · $0 | Optional support; no fixed public support price | Vendor illustration for 1M docs/10M queries: $5k–$9k/month ($3k–$5k infrastructure + $2k–$4k LLM). Not a quote. | Multi-container storage/messaging, compute/GPU, models, OCR and operations | High fixed platform cost; improves economically at scale |
Standard GraphRAG uses models for entity and relationship extraction, entity and relationship summaries, optional claims and community reports. FastGraphRAG replaces much extraction with NLP while retaining model-generated community reports. Microsoft estimates graph extraction at roughly 75% of standard indexing cost.
monthly total = ingestion model calls
+ embedding and reranking calls
+ query-generation calls
+ graph, vector and object storage
+ compute or GPU
+ observability, backups and network
+ engineering and on-call operations
Matrix 06
| Priority | Evaluate first | Compare against |
|---|---|---|
| Learn internals | nano | Microsoft GraphRAG |
| Whole-corpus themes | Microsoft GraphRAG | LightRAG global/mix |
| General self-hosted document GraphRAG | LightRAG | Neo4j ecosystem |
| Multi-hop retrieval research | HippoRAG | KAG |
| Changing agent memory | Graphiti | TrustGraph |
| Formal ontology and deterministic rules | KAG/OpenSPG | TrustGraph |
| Managed property graph | Neo4j/Aura | Graphiti/Zep for agent memory |
| Sovereign full context platform | TrustGraph | LightRAG + selected infrastructure |
| Lowest-cost learning prototype | nano + local models | Graph Builder + AuraDB Free |
Decision method
Hold the generator model constant where possible. Measure retrieval precision/recall, multi-hop accuracy, faithfulness, provenance correctness, ACL leakage, indexing and query cost, update/deletion latency, P50/P95 latency, failure rate and engineer-days to production.
Evidence
Graphiti · KAG · OpenSPG · TrustGraph
Stripe MCP · Stripe AI toolkit · Cerebras Knowledge · CocoIndex code indexing