Is Obsidian free for commercial use?

Yes. As of the February 2025 licence update, Obsidian is free for all use including commercial use. A commercial licence ($50/user/year) is optional and supports development but is not required for individual commercial use. Obsidian Sync (for device sync) costs $4/month billed annually, but free alternatives (iCloud, Dropbox) work for most solo consultants.

Should I use Notion or Obsidian for PKM?

They solve different problems. Notion is excellent for project management, client documentation, and deliverable drafts. Obsidian is better for personal knowledge compounding — its bidirectional linking surfaces connections you didn't explicitly build, which is what makes a second brain compound over time rather than become an archive. Many consultants maintain both: Notion for client work, Obsidian for PKM.

Compare · Knowledge Layer · Brief 66

PKM OS for Solo Consultants:
Notion vs Obsidian vs Roam Research (2026).

Most consultants build archives, not second brains. The difference is structural: bidirectional links surface connections you didn't explicitly build; folder hierarchies require you to remember what you stored. Tool comparison covering Obsidian (free for commercial use since Feb 2025, default recommendation), Roam Research (outliner original, declining momentum), Logseq (open-source Roam alternative), and Apple Notes + Readwise (minimum viable PKM stack). Five decision questions and four archetype configurations. Updated May 2026.

Updated: May 2026 · Pricing verified

The distinction that matters first

A knowledge base is what you share with others. A second brain is what compounds your own thinking over time.

Most solo consultants build archives, not second brains. They capture notes diligently and then never return to them. The archiving trap is not a discipline problem — it is a structural one. Flat folder hierarchies and page-centric databases require explicit navigation. A PKM system is only valuable if notes you took 18 months ago actively surface when you are writing a deliverable today. That is the mechanism that separates a compounding system from an archive.

If you are trying to solve a documentation or knowledge-sharing problem — SOPs, client wikis, onboarding guides — that is a different category. See the Knowledge Base OS. This article covers your private second brain.

The Notion reality check

Notion is excellent for project management, client documentation, and deliverable drafts. Its page-centric, hierarchical structure is a mismatch for atomic note-taking and idea linking. This is not a knock on Notion — it is simply the wrong tool for the PKM job. Keep Notion for what it does well. The question this article answers is whether to add a dedicated PKM layer alongside it.

Tool snapshots

Notion, Obsidian, Roam Research, and the alternatives.

Obsidian — The Default Recommendation for Serious Note-Takers

Local-first, Markdown-based PKM with genuine bidirectional linking, 2,700+ community plugins, and the strongest long-term compounding story of any tool in this space. The core app is free for personal and commercial use — no subscription required, no sign-up. As of the February 2025 licence update, the commercial licence is optional (to support development) but not required for individual commercial use.

Component	Cost
Core app	Free (including commercial use)
Obsidian Sync	$4/mo (annual); free alternative: iCloud or Dropbox
Commercial licence (optional)	$50/user/year — supports development

Why it compounds: True bidirectional linking with a backlinks panel — every note shows all other notes that reference it, surfacing connections you didn't explicitly build. Local Markdown files — portable, version-controllable via git, readable in any text editor, no vendor lock-in. Plugin ecosystem (Dataview, Templater, Readwise integration, Zotero) covers every research and consulting workflow. The honest limitation: Setup investment is real — expect 3–8 hours of initial configuration. Tinkering with the system rather than using it is the primary failure mode for Obsidian users.

Roam Research — The Outliner Original

The tool that introduced daily-notes-first, bidirectional linking, and outliner-based PKM to a mainstream audience. Daily Notes as the default entry point makes it natural to capture thoughts in context. Block-level references allow the same thought to appear in multiple contexts without duplication.

Pricing: $15/month or $165/year. No free tier beyond a 31-day trial. Honest assessment: $15/month with no free tier is hard to justify given declining ecosystem momentum. Obsidian offers the same core linking capability for free. For existing Roam users with a functioning system: no compelling reason to migrate. For new users evaluating tools: Obsidian offers most of Roam's core strengths with better data portability and a larger plugin ecosystem.

Logseq — The Open-Source Alternative

Open-source, block-based outliner similar in paradigm to Roam but with local-first Markdown storage and a growing plugin ecosystem. Free for the core app, with a planned Logseq Pro tier for sync and collaboration. Strong privacy story — all data stays local by default.

Best for: Consultants who want a Roam-like outliner experience with data portability and no subscription cost. A credible alternative to both Roam and Obsidian for outliner-preference users.

Apple Notes + Readwise Reader — Minimum Viable PKM

For consultants who find dedicated PKM tools overwhelming. Readwise Reader ($9.99/month annual) ingests articles, PDFs, newsletters, and web highlights into a unified reading and annotation layer; Readwise's daily review resurfaces key passages over time using spaced repetition. Apple Notes handles quick capture. No bidirectional linking, no graph view — but for consultants who need a lightweight reading and capture layer without configuration overhead, this combination handles 80% of the use case at a fraction of the setup cost.

Best for: The Lightweight Pragmatist archetype. This is explicitly a bridging stack — designed to be graduated out of after 6 months of consistent use, when the Keeper notes become raw material for an Obsidian migration.

Decision framework

Five questions before choosing a PKM tool.

Q1 — How consistent is your current note-taking practice?

Notes daily or near-daily for at least three months → You have the foundation for Obsidian. Notes sporadically or only during active engagements → Start with Apple Notes + Readwise and establish the habit before investing in Obsidian configuration. Setup investment only pays off if the behaviour is already there.

Q2 — Do you prefer outliner-style note-taking or prose-style?

Outliner-preference (think in bullet hierarchies and structured lists) → Roam or Logseq more intuitive than Obsidian. Prose-preference → Obsidian more comfortable. The wrong match creates friction that kills the habit.

Q3 — How important is data portability for long-term security?

If the idea of a company shutting down and taking 10 years of your client notes is intolerable → Obsidian or Logseq (local Markdown files you own). Comfortable with cloud tools → Notion and Roam are viable.

Q4 — Are you already inside Notion for project management?

Yes → The honest question is whether you will actually maintain two systems. Some consultants do this effectively (Notion for client work and deliverables, Obsidian for PKM). Others never build the second-tool habit. Be realistic about your behavioural tendencies before committing to a two-system architecture.

Q5 — Is the goal to extract consulting IP (frameworks, patterns)?

If properly linked notes from multiple client engagements should reveal patterns that become frameworks → Obsidian's bidirectional linking makes this possible. Without bidirectional links, patterns stay invisible in disconnected notes. See the Thought Leadership OS for how PKM connects directly to IP development.

Configurations by archetype

Four PKM setups for four consultant profiles.

Research-Intensive Specialist → Obsidian + Zotero + Readwise Reader

Obsidian vault with a Zettelkasten-adjacent structure: /00-Inbox, /10-Literature-Notes, /20-Permanent-Notes, /30-Projects, /40-Frameworks. Zotero for PDF annotation; Obsidian Zotero Integration plugin pulls annotations into literature notes. Readwise Reader for web articles and newsletters; Readwise-to-Obsidian plugin auto-imports highlights. Dataview plugin for querying notes by client, domain, or tag — generates a view of all notes related to a framework-in-development.

Generalist Client-Advisor → Notion + selective Obsidian

Notion as primary client work environment (engagement database, meeting notes, deliverable drafts). A lightweight Obsidian vault for insight notes only: after each engagement concludes, distill 3–5 atomic "evergreen" observations into Obsidian. Over time, backlinks reveal which observations recur across clients — these are the seeds of frameworks. More overhead than a single-system solution, but preserves Notion's collaborative strengths while adding genuine PKM capability.

Prolific Framework Builder → Obsidian as full PKM OS

Full Zettelkasten vault with atomic permanent notes. Templater plugin with a "Framework Development" template linking a developing framework note to all contributing permanent notes and client observation notes. Canvas view for visual framework mapping. Obsidian as the drafting environment for frameworks; export to Notion or Google Docs for client-deliverable formatting. Readwise integration for highlight import; AI writing tools for synthesis of dense note clusters into draft language.

Lightweight Pragmatist → Apple Notes + Readwise Reader

Readwise Reader as the reading and highlight layer. Apple Notes for meeting capture and client observations — organised minimally with smart folders or tags by client. Weekly review habit: 20 minutes on Friday to promote any notes worth keeping to a "Keeper" folder. After 6 months of consistent use, the Keeper notes are raw material for an Obsidian migration. This is the bridging stack — vastly better than scattered notes, but explicitly designed to be graduated out of.