Memory Providers

Hermes Agent ships with 7 external memory provider plugins that give the agent persistent, cross-session knowledge beyond the built-in MEMORY.md and USER.md. Only one external provider can be active at a time — the built-in memory is always active alongside it.

Quick Start

hermes memory setup      # interactive picker + configuration
hermes memory status     # check what's active
hermes memory off        # disable external provider

Or set manually in ~/.hermes/config.yaml:

memory:
  provider: openviking   # or honcho, mem0, hindsight, holographic, retaindb, byterover

How It Works

When a memory provider is active, Hermes automatically:

1. Injects provider context into the system prompt (what the provider knows)
2. Prefetches relevant memories before each turn (background, non-blocking)
3. Syncs conversation turns to the provider after each response
4. Extracts memories on session end (for providers that support it)
5. Mirrors built-in memory writes to the external provider
6. Adds provider-specific tools so the agent can search, store, and manage memories

The built-in memory (MEMORY.md / USER.md) continues to work exactly as before. The external provider is additive.

Available Providers

Honcho

AI-native cross-session user modeling with dialectic Q&A, semantic search, and persistent conclusions.

Best for	Teams using Honcho's user modeling platform
Requires	pip install honcho-ai + API key
Data storage	Honcho Cloud
Cost	Honcho pricing

Tools: honcho_profile (peer card), honcho_search (semantic search), honcho_context (LLM-synthesized), honcho_conclude (store facts)

Setup:

hermes memory setup    # select "honcho"
# Or manually:
hermes config set memory.provider honcho
echo "HONCHO_API_KEY=your-key" >> ~/.hermes/.env

Config: $HERMES_HOME/honcho.json — existing Honcho users' configuration and data are fully preserved.

Migrating from hermes honcho

If you previously used hermes honcho setup, your config and all server-side data are intact. Just set memory.provider: honcho to reactivate via the new system.

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OpenViking

Context database by Volcengine (ByteDance) with filesystem-style knowledge hierarchy, tiered retrieval, and automatic memory extraction into 6 categories.

Best for	Self-hosted knowledge management with structured browsing
Requires	pip install openviking + running server
Data storage	Self-hosted (local or cloud)
Cost	Free (open-source, AGPL-3.0)

Tools: viking_search (semantic search), viking_read (tiered: abstract/overview/full), viking_browse (filesystem navigation), viking_remember (store facts), viking_add_resource (ingest URLs/docs)

Setup:

# Start the OpenViking server first
pip install openviking
openviking-server

# Then configure Hermes
hermes memory setup    # select "openviking"
# Or manually:
hermes config set memory.provider openviking
echo "OPENVIKING_ENDPOINT=http://localhost:1933" >> ~/.hermes/.env

Key features:

• Tiered context loading: L0 (~100 tokens) → L1 (~2k) → L2 (full)
• Automatic memory extraction on session commit (profile, preferences, entities, events, cases, patterns)
• viking:// URI scheme for hierarchical knowledge browsing

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Mem0

Server-side LLM fact extraction with semantic search, reranking, and automatic deduplication.

Best for	Hands-off memory management — Mem0 handles extraction automatically
Requires	pip install mem0ai + API key
Data storage	Mem0 Cloud
Cost	Mem0 pricing

Tools: mem0_profile (all stored memories), mem0_search (semantic search + reranking), mem0_conclude (store verbatim facts)

Setup:

hermes memory setup    # select "mem0"
# Or manually:
hermes config set memory.provider mem0
echo "MEM0_API_KEY=your-key" >> ~/.hermes/.env

Config: $HERMES_HOME/mem0.json

Key	Default	Description
user_id	hermes-user	User identifier
agent_id	hermes	Agent identifier

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Hindsight

Long-term memory with knowledge graph, entity resolution, and multi-strategy retrieval. The hindsight_reflect tool provides cross-memory synthesis that no other provider offers.

Best for	Knowledge graph-based recall with entity relationships
Requires	Cloud: pip install hindsight-client + API key. Local: pip install hindsight + LLM key
Data storage	Hindsight Cloud or local embedded PostgreSQL
Cost	Hindsight pricing (cloud) or free (local)

Tools: hindsight_retain (store with entity extraction), hindsight_recall (multi-strategy search), hindsight_reflect (cross-memory synthesis)

Setup:

hermes memory setup    # select "hindsight"
# Or manually:
hermes config set memory.provider hindsight
echo "HINDSIGHT_API_KEY=your-key" >> ~/.hermes/.env

Config: $HERMES_HOME/hindsight/config.json

Key	Default	Description
mode	cloud	cloud or local
bank_id	hermes	Memory bank identifier
budget	mid	Recall thoroughness: low / mid / high

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Holographic

Local SQLite fact store with FTS5 full-text search, trust scoring, and HRR (Holographic Reduced Representations) for compositional algebraic queries.

Best for	Local-only memory with advanced retrieval, no external dependencies
Requires	Nothing (SQLite is always available). NumPy optional for HRR algebra.
Data storage	Local SQLite
Cost	Free

Tools: fact_store (9 actions: add, search, probe, related, reason, contradict, update, remove, list), fact_feedback (helpful/unhelpful rating that trains trust scores)

Setup:

hermes memory setup    # select "holographic"
# Or manually:
hermes config set memory.provider holographic

Config: config.yaml under plugins.hermes-memory-store

Key	Default	Description
db_path	$HERMES_HOME/memory_store.db	SQLite database path
auto_extract	false	Auto-extract facts at session end
default_trust	0.5	Default trust score (0.0–1.0)

Unique capabilities:

• probe — entity-specific algebraic recall (all facts about a person/thing)
• reason — compositional AND queries across multiple entities
• contradict — automated detection of conflicting facts
• Trust scoring with asymmetric feedback (+0.05 helpful / -0.10 unhelpful)

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RetainDB

Cloud memory API with hybrid search (Vector + BM25 + Reranking), 7 memory types, and delta compression.

Best for	Teams already using RetainDB's infrastructure
Requires	RetainDB account + API key
Data storage	RetainDB Cloud
Cost	$20/month

Tools: retaindb_profile (user profile), retaindb_search (semantic search), retaindb_context (task-relevant context), retaindb_remember (store with type + importance), retaindb_forget (delete memories)

Setup:

hermes memory setup    # select "retaindb"
# Or manually:
hermes config set memory.provider retaindb
echo "RETAINDB_API_KEY=your-key" >> ~/.hermes/.env

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ByteRover

Persistent memory via the brv CLI — hierarchical knowledge tree with tiered retrieval (fuzzy text → LLM-driven search). Local-first with optional cloud sync.

Best for	Developers who want portable, local-first memory with a CLI
Requires	ByteRover CLI (npm install -g byterover-cli or install script)
Data storage	Local (default) or ByteRover Cloud (optional sync)
Cost	Free (local) or ByteRover pricing (cloud)

Tools: brv_query (search knowledge tree), brv_curate (store facts/decisions/patterns), brv_status (CLI version + tree stats)

Setup:

# Install the CLI first
curl -fsSL https://byterover.dev/install.sh | sh

# Then configure Hermes
hermes memory setup    # select "byterover"
# Or manually:
hermes config set memory.provider byterover

Key features:

• Automatic pre-compression extraction (saves insights before context compression discards them)
• Knowledge tree stored at $HERMES_HOME/byterover/ (profile-scoped)
• SOC2 Type II certified cloud sync (optional)

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Provider Comparison

Provider	Storage	Cost	Tools	Dependencies	Unique Feature
Honcho	Cloud	Paid	4	honcho-ai	Dialectic user modeling
OpenViking	Self-hosted	Free	5	openviking + server	Filesystem hierarchy + tiered loading
Mem0	Cloud	Paid	3	mem0ai	Server-side LLM extraction
Hindsight	Cloud/Local	Free/Paid	3	hindsight-client	Knowledge graph + reflect synthesis
Holographic	Local	Free	2	None	HRR algebra + trust scoring
RetainDB	Cloud	$20/mo	5	requests	Delta compression
ByteRover	Local/Cloud	Free/Paid	3	brv CLI	Pre-compression extraction

Profile Isolation

Each provider's data is isolated per profile:

• Local storage providers (Holographic, ByteRover) use $HERMES_HOME/ paths which differ per profile
• Config file providers (Honcho, Mem0, Hindsight) store config in $HERMES_HOME/ so each profile has its own credentials
• Cloud providers (RetainDB) auto-derive profile-scoped project names
• Env var providers (OpenViking) are configured via each profile's .env file

Building a Memory Provider

See the Developer Guide: Memory Provider Plugins for how to create your own.