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Legal · head to head

Relativity vs Spellbook

Relativity logo

Relativity

Legal

Ediscovery and legal data platform for large matters

From
On request
Rated
-
Full reviewWebsite
Spellbook logo

Spellbook

Legal

Contract drafting and review assistant inside Microsoft Word

From
On request
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Relativity quote-only and expensive, typically billed on data volume, so costs escalate with matter size; Spellbook it publishes no accuracy figure for its own output and no independent evaluation exists, so a firm must run its own assessment on real agreements.
  • They diverge on capability: Relativity covers Large-scale processing, Spellbook covers Word add-in drafting.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Relativity and Spellbook actually diverge.

Attributes where Relativity and Spellbook differ
AttributeRelativitySpellbook
PlatformsWeb, Cloud, Self-hostedWindows, macOS, Web

Identical on both: starting price (On request), pricing model (quote), free tier (No), user rating (Not yet rated), category (Legal).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Relativity

  • Large-scale processing
  • Review workflow
  • Analytics and active learning
  • Application ecosystem

Only in Spellbook

  • Word add-in drafting
  • Contract review
  • Benchmarks against market standards
  • Question answering
  • Named model providers

What people use each for

The jobs each tool is most often brought in to do.

Relativity

  • Large litigation with very high document volumesnot Spellbook
  • Corporate investigations requiring defensible, auditable reviewnot Spellbook
  • Firms whose review process is already built around the platformnot Spellbook

Spellbook

  • Transactional lawyers drafting commercial agreements in Wordnot Relativity
  • In-house teams reviewing inbound contracts without a contract lifecycle systemnot Relativity
  • Lawyers who want a first pass at redlines before applying their own judgementnot Relativity
  • Firms that need to know which model providers process their documents before adopting an AI toolnot Relativity

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Relativity

  • Quote-only and expensive, typically billed on data volume, so costs escalate with matter size
  • Complex enough that certified specialists are a job title, which is a real staffing cost
  • Considerable overkill for small matters, where lighter self-service tools are far cheaper

Spellbook

  • It publishes no accuracy figure for its own output and no independent evaluation exists, so a firm must run its own assessment on real agreements.
  • The ten times more accurate claim originated in a funding announcement as a statement of intent and has no methodology, dataset or baseline behind it.
  • Contract text is processed by third-party model providers, so despite the zero data retention agreements this still needs checking against client confidentiality terms and outside counsel guidelines.
  • Pricing is not published, so seat cost cannot be compared against competitors without booking a demo.
  • It is a drafting assistant rather than a contract lifecycle system, so it does nothing for execution, obligation tracking or renewals.

Pricing, plan by plan

Relativity

On request

No published plan breakdown. See the Relativity review.

Spellbook

On request
  • Spellbook$undefined/year
    • Priced by the number of seats on the licence
    • Rates quoted after a demo, not published
    • Seven day free trial, free access for academic use

Which should you pick?

Choose Relativity if

  • You need large-scale processing.
  • You work on Web, Cloud, Self-hosted.
  • You also want review workflow.
Relativity review

Choose Spellbook if

  • You need word add-in drafting.
  • You work on Windows, macOS, Web.
  • You also want contract review.
Spellbook review

Questions people ask

Is Relativity or Spellbook better?
Neither clearly leads. Relativity starts at On request and Spellbook at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Relativity or Spellbook?
Relativity starts at On request and Spellbook at On request.
Does Relativity or Spellbook run on more platforms?
Relativity runs on Web, Cloud, Self-hosted. Spellbook runs on Windows, macOS, Web.
What is Relativity best used for?
Relativity is most often used for large litigation with very high document volumes, corporate investigations requiring defensible, auditable review, firms whose review process is already built around the platform. Of those, large litigation with very high document volumes and corporate investigations requiring defensible, auditable review are not what Spellbook is typically brought in for.
What can Relativity do that Spellbook cannot?
Relativity covers Large-scale processing, Review workflow, Analytics and active learning, Application ecosystem. Spellbook covers Word add-in drafting, Contract review, Benchmarks against market standards, Question answering.

Answered from the vendors’ own pages

Relativity: What does Relativity cost?

It does not publish rates. Ediscovery is generally billed on data volume and users, quoted per matter or organisation.

Spellbook: Is Spellbook's accuracy independently verified?

No. It publishes no accuracy figure of its own, and no third-party evaluation has been published. It did not participate in the Vals Legal AI Report, the main independent lawyer-baselined benchmark. Evaluate it on your own agreements during the trial.

Relativity: Is Relativity only for law firms?

No. Corporate legal departments and government agencies use it for investigations as well as litigation.

Spellbook: Which models does it use and where does our text go?

Spellbook names OpenAI GPT-5 and Anthropic Claude models, and states it has zero data retention agreements with both providers. Confirm the current terms and subprocessor list against your client confidentiality obligations before use.

Relativity: Do I need trained staff?

In practice yes. Relativity certification is a recognised specialism, and that staffing cost is part of the total.

Spellbook: What does it cost?

Pricing is per seat but is not published. The vendor quotes it after a demo, so the seat rate cannot be compared with competitors in advance.

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