Spellbook vs. LegalOn vs. Luminance: What AI Contract Review Costs and Where It Stops

Unvarnished Reviews Research

Market Position: Three Ways to Sell the Same Idea, and No Price for Any

AI contract review tools read a contract against a team's preferred positions, flag where the draft departs from them and propose redlines or new clauses. Most of the work happens inside Microsoft Word. The three tools here sell that idea three ways: Spellbook per seat, LegalOn by plan with added modules, and Luminance by the volume of documents stored.

All three are well funded. Spellbook raised a $50 million Series B in October 2025 led by Khosla Ventures' Keith Rabois, reported at a $350 million post-money valuation, and says nearly 4,000 law firms and in-house teams in 80 countries use it; its website now says more than 5,000. It added $40 million of debt financing from RBCx in March 2026, reported to be for acquisitions. LegalOn raised a $50 million Series E in July 2025 led by Goldman Sachs Alternatives, bringing total funding to $200 million, and reports more than 9,000 customers in August 2026, up from 7,000 a year earlier. It bought the governance company Fides in October 2025. Luminance raised a $75 million Series C in February 2025 led by Point72, and reports more than 1,000 enterprises in over 70 countries. Customer counts are vendor claims and are counted differently, so they do not compare.

The finding that should change how any of the three is budgeted: none publishes a rate, the figures that circulate come from competitors and conflict by as much as 25x for one product, and the accuracy evidence comes mostly from the vendors. A buyer comparing the three is comparing three quotes that have not been written, against accuracy claims that have not been independently tested.

What Each Platform Does

All three apply a team's positions to contracts, flag risk and suggest redlines. They differ in where the work happens, how far past review the product reaches and what unit the vendor bills. The descriptions below come from the vendors' pages, so they show what the vendors say, not what independent testing found.

Spellbook

Spellbook is an AI assistant for transactional lawyers that works inside Microsoft Word. It redlines incoming contracts and tracks each suggestion, drafts clauses and full agreements from AI or saved precedent, compares a contract against market standards, and answers questions about the document. Playbooks turn a team's standards into checklists applied to every review. Associate is an agent for multi-document work, and press coverage reports that the product runs on OpenAI's GPT-5.

Its integration list names Word, Google Docs, Slack, OneDrive, Dropbox, SharePoint, Google Drive and iManage. Autonomous Contract Management, covering intake, drafting, review and a repository of signed contracts, is listed as early access. The site lists SOC 2 Type II, HIPAA, GDPR and EU AI Act compliance, single sign-on and multi-factor authentication, and says its model providers do not train on, store or learn from customer data. It does not list ISO 27001.

LegalOn

LegalOn is a contract review and legal operations platform for in-house teams, sold in three plans. Core Review includes unlimited AI contract review and redlining, 135 or more pre-built playbooks, an AI assistant, a document repository and a Word add-in. Contracting Suite adds custom playbooks, a contract vault, onboarding and enterprise single sign-on. Productivity Suite adds matter management, intake and triage agents, and intake through email, forms, Slack and Microsoft Teams.

Entity management and board management came with the Fides acquisition, and translation, international playbooks and managed playbooks are listed without a plan. Native integrations are Word, Slack, Teams and SharePoint, with Google Drive and Box marked coming soon, plus a contract and matter API. LegalOn lists ISO 27001, ISO 27011 and SOC 2 Type II, says its private AI does not use customer data to train third-party foundation models, and says it has a collaboration with OpenAI.

Luminance

Luminance calls itself a contract intelligence platform for legal, procurement, finance and sales teams. Its pages describe three products: Negotiate, which brings precedent and playbooks into redlines, Discover, which searches a repository for risks and obligations, and Automate, which runs workflows from intake to signature. A January 2026 release added memory of negotiation history and an assistant called Ask Lumi, launched in beta with design partners that included Deloitte and Quantinuum.

It describes a proprietary model, Luna Crescent, and a routing layer that sends each task to a suitable model, with a validation layer it calls a panel of judges. Its pages list ISO 27001 and SOC 2 Type II, and its Master Agreement says some features send inputs to third-party model providers at the customer's direction. The product is also sold as a private offer on AWS Marketplace. Deployment options and integrations are not described on the pages reviewed.

How the Three Differ

The practical differences are three. Spellbook is the lightest to start, since it lives in Word and offers a trial, but it is a drafting and review tool and not a platform for matters or governance. LegalOn is the broadest of the three for an in-house department, since it adds intake, a contract vault, entity and board records, and it names what each plan includes. Luminance is built for volume and negotiation at enterprise scale, and its pages say the least about deployment and integrations. Price does not separate them in public, because none publishes a rate; the sections that follow show what is reported and where it conflicts.

Where Other Tools Fit

Two other groups come up in the same buying conversations, and both are covered in separate reports on this site.

• General legal AI platforms. Harvey, CoCounsel and Legora cover research, drafting and review for law firms and legal departments, and none publishes a price either. See Harvey vs. CoCounsel vs. Legora.
• Full contract lifecycle platforms. Ironclad, DocuSign CLM and Icertis manage contracts from request to renewal, and the question is whether a team needs that scope at all. See Ironclad vs. DocuSign CLM vs. Icertis.

The practical split: a team that needs help with review and drafting in Word starts with the tools here, a team that needs lifecycle administration starts with the CLM report, and a law firm doing research and drafting across matters starts with the legal AI report.

Spellbook: The Upside

It is the easiest to try. Spellbook offers a 7-day self-serve trial, installs in Word, and says it works without the lengthy rollouts of enterprise platforms. Users rate it 4.7 of 5 across 29 reviews on a business review site, the largest review base of the three there.

Its terms are the most specific about money. Renewal increases are capped at 10% a year unless the product's functionality materially changes, customers keep ownership of their data and outputs, and personalization data stays within the customer's account. It lists SOC 2 Type II, HIPAA, GDPR and EU AI Act compliance.

The company is growing and funded. A $50 million Series B at a reported $350 million valuation, a customer count the vendor puts at more than 5,000, and an exclusive drafting partnership with the Canadian Bar Association reported in March 2026 point to a vendor that will be around for a contract term.

Spellbook: The Downside

The cancellation terms are strict. Orders renew automatically for 12 months unless either side gives notice 30 days ahead. A customer can end the contract for convenience with 30 days' notice, but all fees for the rest of the term become due. Subscription fees are non-cancelable and non-refundable, and the scope cannot be reduced mid-term. The FAQ adds that sales-assisted trials may convert to paid automatically.

Review evidence is mixed and thin. A consumer review site shows a 2.7 of 5 score from 10 reviews, with complaints about unsolicited sales calls, a free trial that was not available, output quality and unhelpful support, and one reviewer said the playbook and benchmark tools suggest many irrelevant changes. Ten reviews is a small sample, and another reviewer praised the Word integration. Lawyerist's June 2026 review gave it 4.1 of 5 and shows no testing method.

The scope is narrow, and data leaves the building. Spellbook is for contracts and not case law research, per Lawyerist. Prompts and document data are sent to third-party language models, which the terms say must delete them once the output returns, and Spellbook keeps the right to create anonymized derived data it owns.

LegalOn: The Upside

It reaches the furthest past review. One vendor covers contract review, a contract vault that tracks key terms and obligations, matter intake and triage, and, since the Fides acquisition, entity and board management. A team that wants one system for legal requests and contracts can buy it without assembling parts.

It is the clearest about what is in each plan. The three plans are named, with features listed for each, usage described as unlimited, business users covered by view-only licenses in the suites, and ISO 27001, ISO 27011 and SOC 2 Type II listed for every plan. Customer growth is steady by the vendor's count: 7,000 customers in July 2025, 8,000 in February 2026 and more than 9,000 in August 2026.

LegalOn: The Downside

The data-return terms are weak. After a subscription ends, LegalOn may delete or disable access to customer content after 30 days and has no obligation to keep it. Export is available during the term through available tooling, and the terms do not guarantee a return of data afterward. Prepaid fees are not refunded on termination.

Renewal prices are uncapped. LegalOn may raise renewal pricing with 30 days' notice, and introductory discounts do not carry into renewal. The pricing page does not say which modules, including entity management, board management, translation and managed playbooks, come with a plan and which are sold separately.

Independent evidence is the thinnest of the three. Users rate it 5.0 of 5 from 10 reviews on one business review site and another lists no reviews, and the accuracy benchmark that ranks LegalOn first was designed and run by LegalOn. The vendor's claim that review is up to 85% faster has no outside test behind it.

Luminance: The Upside

It has the strongest evidence of enterprise use. Gartner Peer Insights shows 4.5 of 5 from 33 ratings with no rating below 4 stars, and one Gartner page scores service and support at 4.9. Named customers include AMD, Hitachi, Staples and SiriusXM, and a February 2025 report said more than a quarter of the top 100 global law firms used its technology.

It is the least dependent on one model provider. Luminance describes a proprietary model and a routing layer that is not tied to a single provider, and its chief executive has said owning models protects margins and reduces exposure to supplier pricing. It reports revenue doubling in 2025, a vendor figure with no audit behind it.

Luminance: The Downside

The contract favors staying. The Master Agreement renews automatically for periods equal to the initial term, which can be multi-year, unless notice arrives at least 90 days before the term ends. Renewal fees can rise by the consumer price index plus 3 percentage points a year. Annual uploads are capped at 200% of the document allowance regardless of deletions.

Leaving is the most constrained. For EU customers, early termination triggers exit charges equal to the remaining unpaid fees for the full term. After the contract, customer data stays available during a retention period the agreement does not define, then is deleted and cannot be recovered. The agreement does not address export formats.

It is priced and built for enterprises, and the newest product is unproven. A Gartner reviewer called it sized and priced for enterprises and challenging for smaller firms. The January 2026 relaunch started in beta with design partners, so buyers should confirm which features are generally available. A major software-review site lists no user reviews of it.

Platform Ratings at a Glance

All three review bases are small, between 10 and 33 ratings per site, so a 0.4-point gap means little. Ratings run from 2.7 to 5.0 depending on the site, which is itself the finding: no source gives a sample large enough to settle the choice, and the highest rating has the fewest reviews.

Pricing (October 2026)

None of the three publishes a price. Vendor pages were checked in October 2026 and show quote-only pricing or plan names without prices. Every dollar figure below comes from pages published by competing vendors or advisory sites that cite unnamed sources, and none is confirmed by Spellbook, LegalOn or Luminance.

Reported estimates, by source type

The AWS Marketplace listing for Luminance shows a placeholder of $9,999,999 for a 36-month contract, which reflects a private-offer-only listing and not a price. The spread across the Spellbook estimates is about 25x, from $20 to $500 per user per month, and the sources do not agree on whether a seat minimum exists.

TCO Comparison: A 10-User Legal Team, 3 Years

No vendor publishes a rate, so the totals below are modeled from the reported estimates and labeled as such. Spellbook uses $99 as the low rate and $500 as the high rate per user per month, which excludes the two entry-tier prices because the sources do not say they cover a full contract-review team. LegalOn uses $3,500 and $8,000 per user per year. Luminance does not bill by user, so the scenario uses its reported average deal of $42,857 a year, which is not tied to 10 users. Renewal increases use each contract's stated terms where they exist: Spellbook's 10% cap, Luminance's consumer price index plus 3 percentage points at an assumed 3% index, which is 6% a year. LegalOn's terms set no cap, so its increase is not modeled.

No sticker price exists, so no multiplier against an advertised figure can be stated. The spread is the finding: Spellbook's high estimate is 5.1x its low one, LegalOn's is 2.3x, and Luminance's implementation estimate would add 1.2x-1.5x to the first-year license. A single modeled total would hide that range. A buyer should ask each vendor to price the same 10 users, the same contract term and the same modules, with renewal caps written in.

Annual license cost by team size

Treat the larger rows as an upper bound. No vendor publishes a volume discount, buyers at this scale negotiate, and LegalOn's suites include view-only licenses for business users, which would lower the count of paid seats. The rows show only how far the reported estimates could move a budget, from five figures to seven.

Costs the Pricing Table Misses

• Fees due after you cancel at Spellbook. Ending the contract for convenience still makes all fees for the rest of the term due, and fees are non-refundable. A buyer who leaves after six months of a 12-month term pays for the other six.
• Renewal increases at all three. Spellbook caps increases at 10% a year, Luminance at the consumer price index plus 3 percentage points, and LegalOn sets no cap and does not carry introductory discounts into renewal.
• Modules that may not be in the plan. LegalOn lists entity management, board management, translation, international playbooks and managed playbooks without saying whether a plan includes them, and one competitor page reports Luminance's six modules as separately licensed.
• Implementation and training at Luminance. A competing vendor estimates 20%-50% of the first-year license, which is $8,571-$21,429 on the average deal. Luminance publishes no implementation fee or timeline, and a competitor's page says rollouts take two to three months.
• Cloud costs and document caps at Luminance. The AWS Marketplace listing says infrastructure costs may apply, and annual uploads are capped at 200% of the document allowance whatever is deleted.
• Playbook-building time. Every tool applies a team's positions, so legal staff must write and maintain them. LegalOn custom playbooks start at Contracting Suite, and a reviewer of one tool called the output generic until the playbook is built.
• Lawyer review time. ABA Formal Opinion 512 requires a lawyer to understand a tool's risks and keep client information confidential, and lets a lawyer bill for time spent reviewing output but not for learning the tool. Verification does not disappear, so a savings claim should be tested against review time.

Exit and Switching Costs

• Spellbook: pay for the term, keep your files. Cancellation requires 30 days' notice, and the remaining fees come due. Documents stay in the customer's systems, and Spellbook's FAQ says it does not store files, though the terms say prompts and document data go to third-party models and quality-assurance data is deleted after 90 days. The terms describe no export process, and trial projects in Associate become inaccessible after a trial unless the customer upgrades.
• LegalOn: export during the term only. Customers can export content through available tooling while subscribed, and after termination LegalOn may delete or disable access after 30 days with no duty to return it. A customer can terminate within 30 days of a modification notice that materially and adversely affects it, and prepaid fees are not refunded.
• Luminance: the longest tail. Renewal repeats the initial term unless notice arrives 90 days before the end. EU customers who end early owe the remaining fees, data stays available for an undefined retention period and is then deleted without recovery, and backups persist for 14 to 28 days. The agreement does not address export formats.
• Playbooks are the real lock-in. A team's positions, once written into a vendor's format, are the work product that took the longest to produce. None of the three terms reviewed describes a playbook export, so ask for one in writing before signing.

Complexity Comparison

The ratings and vendor pages do not give reliable implementation times for any of the three, and the figures that exist come from competitors. The practical advice is to run a pilot on a real contract set before signing: ask each vendor to review 20 of your agreements against your positions, and compare what a lawyer would still change.

Where AI Contract Review Stops

• The accuracy evidence is vendor-run. LegalOn's 2026 benchmark compared 11 AI models with LegalOn across 3,282 pairwise reviews on 21 provision types, and LegalOn ranked first on all 21. LegalOn designed the test, chose which model represented each company and used a judge model it did not name. LegalOn also ran about 21-25 checks per contract while the baselines ran one pass, so the gap may reflect workflow and not the underlying model. Spellbook and Luminance publish no comparable figures.
• The one independent study did not test them. Vals AI's February 2025 report found a lawyer baseline of 79.7% on redlining against 53.6% for Vincent AI and 65.0% for Harvey Assistant (the report's notes give 59.4%), and said tools did better on plain clause text than on formatted redlined documents. Spellbook, LegalOn and Luminance were not in it. It is a US-only snapshot that used an AI judge, and Vals has a customer relationship with participants. It is evidence about the task, not about these tools.
• The contracts say the same thing. Spellbook's terms call outputs probabilistic and not legal advice and disclaim accuracy. LegalOn's terms say it is neither a law firm nor an attorney and that the customer is solely responsible for reviewing and using output. Liability is capped at fees paid in the prior 12 months at Spellbook and LegalOn, and Luminance's general cap is the same, with three times that for data clauses.
• Professional duties stay with the lawyer. ABA Formal Opinion 512, issued July 29, 2024, ties competence, confidentiality, informed client consent and fees to a lawyer's use of generative AI tools. The tools can cut drafting and first-pass review time, and a lawyer still checks every change.
• A tool applies positions only if someone has written them. All three take a team's standards and apply them to contracts. A team with no written positions gets generic output until it builds them, and Spellbook is described as a tool for contracts, not case law research.

Red Flags

Each finding below is sourced and material enough to influence a purchasing decision.

The Decision Framework

Choose Spellbook if:

• Your lawyers work in Word, want to test within a week, and can accept a term that renews for 12 months with fees due if you leave.
• You have a written quote for your seat count and a pilot on your contracts.
• You are comfortable with prompts going to third-party models under the vendor's stated deletion terms.

Choose LegalOn if:

• You are an in-house team that wants review, matter intake, a contract vault and governance from one vendor, and you have a line-item quote that says which modules are included.
• You have negotiated a renewal cap and a data-return and playbook export clause.
• You tested its review on your agreements instead of relying on its benchmark.

Choose Luminance if:

• You are a large legal team with volume and negotiation needs, and you have a quote by document volume with implementation costs stated.
• You have negotiated the renewal term, the notice period, the cap on increases and the retention period.
• You have confirmed which of the January 2026 features are generally available.

Key Decision Factors

Design decides what you are buying. Spellbook is a Word-based review and drafting assistant, LegalOn is a review platform with matters, a vault and governance, and Luminance is an enterprise contract intelligence platform built around volume and negotiation.

Audience decides which one fits. Spellbook suits lawyers and small teams that want to start fast in Word. LegalOn suits in-house departments that want one system for requests and contracts. Luminance suits large legal teams that can write a custom contract and run a longer rollout.

The missing prices and the unaudited accuracy decide the risk, and the Red Flags decide what to ask. None of the three publishes a rate, the reported figures conflict by as much as 25x for Spellbook, and a 10-user, 3-year model spans $35,640-$180,000 for Spellbook and $105,000-$240,000 for LegalOn before increases. The accuracy proof is vendor-run, and the one independent redlining study found lawyers ahead of the AI tools tested, none of which were these three. Spellbook's risk is a strict term, LegalOn's is weak data-return terms and uncapped renewals, and Luminance's is a long renewal and exit charges. No product here is perfect: Spellbook trades depth for speed to start, LegalOn trades contract flexibility for breadth, and Luminance trades simplicity for scale. Get the price, renewal cap, data-return terms and a playbook export in writing, and run each vendor on 20 of your contracts before signing.

The Bottom Line

• A lawyer or small team that works in Word and wants to start this week should try Spellbook, and get the seat price, the term and the cancellation fees in writing before the trial ends.
• An in-house department that wants review, matters and governance on one vendor should consider LegalOn, with a line-item quote, a renewal cap and a data-return clause.
• A large legal team that negotiates at volume should consider Luminance, and negotiate the renewal term, the retention period and the implementation cost before signing.

Free trials and test-drives. Spellbook offers a 7-day self-serve trial, and its FAQ warns that sales-assisted trials may convert to paid automatically, so cancel in writing before the end date if you are not buying. LegalOn is evaluated through a demo and a custom quote. Luminance offers a two-week free trial on your documents. Ask LegalOn for a paid pilot on your contracts, with a written success test and exit terms if the pilot fails. Use the trial and the pilots as part of your evaluation.