Best AI Contract Review Software for Small Law Firms (2026): Spellbook vs Gavel Exec vs LegalOn
Prices and facts checked October 13, 2026. We don't accept payment for rankings.
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Short answer: for most solo and small-firm transactional lawyers, Gavel Exec is the easiest to start with: a published $160 per user per month (or $1,740 a year), 25 free queries with no card or sales call, and month-to-month billing. Spellbook is the most established Word-native contract AI, used by nearly 4,000 firms and legal teams, but pricing is quote-only. LegalOn suits lawyers who want a large library of ready-made review playbooks.
Our picks
- Best for solo and small firmsGavel Exec: $160/user/mo or $1,740/yr; 25 free queries See Gavel Exec
- Most established Word add-inSpellbook: quote-based; 7-day free trial See Spellbook
- Best ready-made playbook libraryLegalOn: quote-based, Core Review plan for solos See LegalOn
Comparison table
| Gavel Exec | Spellbook | LegalOn | |
|---|---|---|---|
| Price | $160/user/mo, or $1,740/user/yr | Quote, by number of users | Quote, by team size and features |
| Commitment | Month to month | Reported 6-month minimum (per Gavel) | Not published |
| Free trial | 25 free queries per user, no card | 7 days | Demo |
| Works in | Word and browser | Word add-in plus Associate agent | Not stated on pricing page |
| Playbooks | Built-in, uploaded or AI-generated | Yes; Playbook Build Service for in-house | 135+ playbook library |
| Usage cap | 1,000 completions/month | Not published | Unlimited assistant chat (Core Review) |
| Ownership | Acquired by Relativity, June 2026 | Independent; $50M Series B (Oct 2025) | Independent |
Sources: Gavel Exec pricing; Spellbook pricing; LegalOn pricing; LawSites; SiliconANGLE.
1. Gavel Exec: best for solo and small firms
Price: $160 per user per month, or $1,740 per user a year (about $145 a month). Team pricing is available from 10 seats. Paid plans include full-agreement redlining in Word, clause drafting, 1,000 completions a month, automatic playbook runs, benchmarking against market data and priority-ranked redlines. You can start with 25 free queries per user, no card required (Gavel Exec pricing).
Ownership change: Relativity, the eDiscovery company, acquired Gavel in June 2026. Relativity says Gavel will keep running as usual for now, and plans to fold its capabilities into RelativityOne over time. LawSites notes the future of "products, pricing and customers" remains to be seen (LawSites).
Watch for: with an acquisition in progress, prefer monthly billing until the roadmap is clear.
2. Spellbook: most established Word add-in
Price: custom, "structured around the number of team members on your license," and you need a demo for a quote. Lawyers can try it free for 7 days. The Law Firms plan includes the Word add-in, the Associate multi-document agent, group training and support (Spellbook pricing).
Gavel's comparison page claims Spellbook quotes run about $380 per seat per month with a 6-month commitment. That's a competitor's figure based on user reports, so get your own quote (Gavel).
Track record: Spellbook raised a $50 million Series B in October 2025 at a $350 million valuation. It says it serves nearly 4,000 law firms and in-house teams in 80 countries and has reviewed more than 10 million contracts. It runs on OpenAI's GPT-5 and can search your own deal history in OneDrive or Dropbox for precedent clauses (SiliconANGLE).
Watch for: confirm the minimum term and per-seat price in writing before the trial ends.
3. LegalOn: best ready-made playbook library
Price: quote-based, "priced around your team size and the capabilities you need." The Core Review plan, which LegalOn positions for solo attorneys and fractional GCs, includes AI contract review and drafting, unlimited chat with its legal AI assistant, and a library of 135+ playbooks. Higher suites add custom playbooks, a contract repository and matter management for in-house teams (LegalOn pricing).
Best fit: lawyers who review many standard agreements (NDAs, MSAs, vendor contracts) and want a pre-built checklist rather than writing their own playbooks.
How to evaluate any contract AI
- Run your own contracts. Use the trial on three agreements you've already negotiated and compare the AI's redlines with yours.
- Check confidentiality terms. Make sure client documents aren't used for training, and that retention fits your obligations under ABA Formal Opinion 512.
- Mind the state rules. In California, SB 574 restricts putting confidential information into public AI systems.
- Keep a human in the loop. AI-suggested clauses and "market standard" benchmarks are starting points, not advice.
Which should you choose?
| If you… | Choose |
|---|---|
| Are a solo or small firm and want a published price | Gavel Exec |
| Want the most widely used Word add-in, and a quote is fine | Spellbook |
| Review lots of standard agreements and want ready playbooks | LegalOn |
| Also need research and litigation tools | See best AI tools for small law firms |
| Wonder whether ChatGPT is enough | Read legal AI vs ChatGPT |
FAQ
How much does Spellbook cost?
Spellbook doesn't publish prices. A competitor reports user quotes of around $380 per seat per month with a 6-month commitment. Get a written quote.
Is there a free AI contract review tool?
Gavel Exec includes 25 free queries per user, and Spellbook has a 7-day free trial. General chatbots can summarize contracts, but check their confidentiality terms first.
Will AI replace contract review by lawyers?
No. These tools speed up first-pass review and redlining, but lawyers remain responsible for the advice. See will AI replace lawyers.
Sources
Pages we used for this article, checked on or before the update date above.
- Gavel Exec pricing · gavel.io
- Spellbook pricing · spellbook.com
- LegalOn pricing · legalontech.com
- LawSites · lawnext.com
- SiliconANGLE · siliconangle.com
- Gavel · gavel.io
Changelog: Oct 13, 2026: first published.