What Spellbook does well.
Solo practitioners and small firms get meaningful leverage out of Spellbook on day one, with no setup beyond installing the add-in.
If your firm's need is inside Word, the $499 AI-Ready Audit still checks whether a build reaches further than Spellbook does for your specific workflow.
Where Spellbook is the right answer.
Three patterns:
The transactional or corporate practice that wants AI in Word, not in a separate tool. Spellbook's strength is the seamless Word integration. Attorneys keep their muscle memory; the AI shows up where they're already drafting.
The firm whose contract patterns are mostly standard. Spellbook is trained on a broad corpus of contracts. Firms whose work fits common patterns (NDAs, service agreements, SaaS contracts, employment) get most of the value the off-the-shelf product provides.
The firm that doesn't have a deep clause library. Spellbook brings its own benchmarks. Firms without strong internal precedent libraries benefit from that breadth.
If none of these three patterns fit your firm, the $499 AI-Ready Audit is the next step rather than a Spellbook trial.
Where custom AI is the right answer.
Custom AI is the right answer for a law firm in three situations, each checked against the firm's own workflow in the $499 AI-Ready Audit:
The firm with a deep, differentiated clause library. If your firm's competitive edge is your forty years of M&A precedents, your specific deal terms, your specific opposing-counsel patterns: Spellbook's generic training dilutes that edge. Custom AI on top of iManage or NetDocuments trains on your archive specifically.
The firm whose AI need extends beyond drafting. Spellbook is great for drafting and review. The leakage at most mid-market firms is in time capture, intake, matter summarization, and knowledge retrieval, workflows Spellbook doesn't address.
The firm with strict data-residency requirements. Spellbook ships data through their cloud. Custom AI runs in the firm's own Azure or AWS tenant (a private cloud account) under NDA (a signed non-disclosure agreement), with permissions and ethical walls preserved.
the $499 AI-Ready Audit is where this fit gets checked against your firm's own intake, triage and billing workflow. A working prototype on the firm's own documents runs before any build fee is due, so the risk is checked before it is paid for; for the wider buy-versus-build question, see renting AI versus owning it.
What we recommend.
The Spellbook-versus-custom-AI recommendation for a law firm depends on the firm's own profile, sized in the $499 AI-Ready Audit. A transactional or corporate practice with mostly standard contract patterns should try Spellbook for 60 days at the per-seat tier; it is plausibly all that firm needs.
If your firm is litigation-heavy, has deep precedent value to preserve, has data-residency constraints, or has leakage workflows beyond drafting, run the Billable-Hour Recovery Diagnostic. The number on screen will tell you whether the leverage is in drafting (Spellbook fits) or somewhere else (custom commission fits).
Spellbook sits beside document comparison rather than replacing it, so if the renewal in front of you is Litera Compare, the Litera alternatives page covers Draftable, Word's native Compare and the three former competitors Litera has since absorbed, with every figure labelled verified or reported.
the $499 AI-Ready Audit turns this recommendation into a scoped decision for your own firm. For the industry-wide picture, see the law firm industry brief.