What this is
Three legal AI tools dominate the 2026 buying conversation: Harvey (AI-native, Am Law-focused), CoCounsel (Thomson Reuters' Westlaw-integrated AI), and Spellbook (mid-market contract drafting). They overlap in some capabilities but win different segments. This page is a 2026-05-15 head-to-head.
Side-by-Side Matrix
| Dimension | Harvey | CoCounsel (Thomson Reuters) | Spellbook |
|---|---|---|---|
| Category | AI-native generalist | Incumbent + AI (Westlaw integrated) | Contract drafting (Word add-in) |
| Latest valuation / status | $11B (Mar 2026) | Thomson Reuters public | ~$350M (Series B) |
| ARR | ~$190M (Jan 2026) | n/a (segment within TR) | n/a (private) |
| Customer base | 100,000+ lawyers, 1,300 firms incl. Am Law 100 majority | Westlaw + Practical Law base | 4,000+ legal teams |
| Sweet spot | Big Law, Am Law 100 | Mid-large firms on Westlaw | Solo, small firm, in-house mid-market |
| Core capability | Research, drafting, due diligence, M&A workflows | Research, drafting tied to Westlaw corpus | Contract drafting + clause library in Word |
| Hallucination rate (independent eval) | ~17% (community estimate) | ~33% (Westlaw AI-Assisted, Stanford 2025) | n/a (no published independent eval) |
| Westlaw / Lexis integration | Indirect | Native to Westlaw + Practical Law | External clause library |
| Word integration | Yes | Yes | Native Word add-in |
| Pricing | Enterprise quote (~$2-5K/user/yr) | Enterprise quote (CoCounsel module within Westlaw) | $99-299/user/mo |
| Best for | Big Law deals + complex research | Mid-large firms standardising on Westlaw | Day-to-day contracts, in-house counsel |
Best-Use Scenarios
| Scenario | Pick |
|---|---|
| Am Law 50 firm doing M&A diligence + complex research | Harvey |
| Mid-large firm standardising on Westlaw | CoCounsel |
| In-house counsel handling 50+ contracts/month | Spellbook |
| Solo or small firm on tight budget | Spellbook |
| Litigation discovery + research-heavy workflows | Harvey or CoCounsel |
| Contract drafting with custom clause library | Spellbook |
| Firm with existing Lexis+ AI subscription | Lexis+ AI (not in this comparison) or Harvey on top |
Six Things the Comparison Tells You
- Harvey wins Big Law. 100,000+ lawyers and a majority of the Am Law 100 is institutional validation that no competitor matches.
- CoCounsel wins where Westlaw is already deployed. The integration is the moat; competitors can match capability but not the data integration.
- Spellbook wins mid-market by ergonomics. 4,000+ legal teams adopted Spellbook because the Word add-in form factor lowers the friction for non-Big-Law buyers.
- Most firms run multiple tools. Harvey + CoCounsel + Spellbook is a common stack in firms above 50 lawyers.
- Hallucination rates differ. Stanford 2025 data put Westlaw AI-Assisted at 33% and Lexis+ AI at 17%; community estimates put Harvey at ~17%. All require lawyer review.
- Pricing reflects target segment. Harvey enterprise quotes (~$2-5K/user/yr) vs Spellbook self-serve ($99-299/user/mo) is a 4-12x price spread reflecting target segment.
How to Pick
Big Law: Harvey. Westlaw shop: CoCounsel. Mid-market or in-house counsel doing contracts: Spellbook. Many firms above 50 lawyers run all three; below 10 lawyers, Spellbook alone is usually enough.
Methodology
Funding and customer-base data sourced from each vendor's announcements and public filings (Thomson Reuters). Hallucination data from the Stanford 2025 Magesh et al. study on legal AI hallucination rates. See the Legal AI Tools Landscape 2026 research page for the full breakdown.