
The AI workspace where teams and agents get work done together
Goodnotes records 3,227,341 monthly visits with +10.8% month-over-month growth and Freemium, Free Trial pricing. HydraDB OSS records 29,635 monthly visits with +5.8% growth and Freemium, Contact for Pricing pricing.

Graph database built on object storage for agent memory and context
| Dimension / Metric | ![]() | ![]() |
|---|---|---|
| Official Domain | goodnotes.com | hydradb.com |
| Pricing Model | Freemium, Free Trial | Freemium, Contact for Pricing |
| Monthly Visits | 3.23M (3,227,341) | 29.64K (29,635) |
| MoM Traffic Delta | +314.75K (+10.8%) | +1.61K (+5.8%) |
| Primary Market & Share | 🇺🇸 United States (33.8%) | 🇮🇳 India (65%) |
| Direct Visits / mo | 1.64M | 17.15K |
| User Rating | 4.4 | 4.4 |
| Supported Platforms | Website | Website |

Handwritten notes, PDF markup, and AI study tools on one canvas
Low-latency ink with palm rejection, cross-out to erase, and handwriting-to-text conversion keeps writing close to pen on paper.
Import contracts, papers, or textbooks and mark them up by hand, with searchable annotations and clean exports.
Search across typed text, handwriting, and sketches, and turn notes into summaries, mind maps, or structured plans.
Work together in shared notebooks, documents, and whiteboards simultaneously, without version conflicts or file ping-pong.

Graph database built on object storage for agent memory and context
Graph, WAL, value, and index data all live in S3-compatible storage with a hot/warm/cold tiering strategy, cutting infrastructure cost dramatically versus memory-resident graph databases.
One query can traverse graph relationships and run vector, BM25, and reranked search together, so agents do not have to orchestrate four separate systems.
Every change is tracked, letting agents recall what happened, when, and in what sequence, which supports auditability and long-running agent workflows.
OpenCypher over Bolt plus an HTTP API and SDKs make it approachable for teams already familiar with property graphs.

The AI workspace where teams and agents get work done together
SpecialistExcels at automatically generating flashcards and practice quizzes from study notes, but lacks freehand drawing features.
SpecialistExcels at automatically generating flashcards and practice quizzes from study notes, but lacks freehand drawing features.

SpecialistTurns course materials into interactive AI study tools, but focuses less on handwritten digital notebooks.
SpecialistTurns course materials into interactive AI study tools, but focuses less on handwritten digital notebooks.

SpecialistStronger online PDF editing and AI chat capabilities, but lacks tablet-optimized handwritten note-taking workflows.
SpecialistStronger online PDF editing and AI chat capabilities, but lacks tablet-optimized handwritten note-taking workflows.
SpecialistConverts notes and PDFs into quizzes and flashcards, but lacks stylus-based handwriting and sketching tools.
SpecialistConverts notes and PDFs into quizzes and flashcards, but lacks stylus-based handwriting and sketching tools.
Provides gorgeous structured block-based document editing, but is built for typed text rather than handwritten notes.
Provides gorgeous structured block-based document editing, but is built for typed text rather than handwritten notes.

Organizes notes into interconnected typed objects rather than traditional notebooks, but lacks handwritten ink support.
Organizes notes into interconnected typed objects rather than traditional notebooks, but lacks handwritten ink support.
The managed vector database and knowledge engine for production AI
SpecialistUses an infinite visual canvas for note organization, but lacks Goodnotes' paper templates and PDF annotation polish.
SpecialistUses an infinite visual canvas for note organization, but lacks Goodnotes' paper templates and PDF annotation polish.

Offers spatial whiteboards for organizing complex research, but lacks Goodnotes' freehand handwriting stylus support.
Offers spatial whiteboards for organizing complex research, but lacks Goodnotes' freehand handwriting stylus support.

A memory and continual-learning engine that gives any AI agent persistent context
A memory and continual-learning engine that gives any AI agent persistent context
Free / Open-sourceOpen-source AI memory that reasons, not just stores