Antidote

What it is

Antidote is a billing-compliance layer for large law firms. It sits on top of the firm’s existing time-recording and practice management systems and reads every time entry. It checks each entry against the client’s outside counsel guidelines (OCGs) and the firm’s own billing standards, then suggests a compliant rewrite. The point is timing: the check runs as soon as an entry lands in the time system, not weeks later at pre-bill or after an e-billing portal rejects the invoice.

Rules are not configured by hand. Antidote ingests OCG documents, internal guidelines, and historical billing data and builds what it calls Individual Client Standards for each client. Because it reads payment history, it can learn what a client actually pays for as well as what the guideline says. Typical flags are block billing, vague narratives, banned tasks (billing for legal research when the client forbids it), missing task codes, rate caps, and staffing limits. Lawyers get the flags by email, for example a Monday digest saying three of last week’s 21 entries were flagged. They can accept the AI rewrite in one click without logging in. Billing teams work in a web interface.

Antidote is based in London and was founded in 2024. Nicholas d’Adhemar (CEO) and Matt Lyons (CTO) previously ran Apperio, the legal-spend platform PERSUIT bought in May 2025. On January 21, 2026 it announced a $5M seed led by Lakestar, with Concept Ventures and The LegalTech Fund, for $7M raised in total. The money is earmarked for product development and US expansion. It says law firms in the US, UK, and Australia use it, but it names no customers.

Why legal ops teams look at it

• Write-downs start at the time entry. Antidote’s own model assumes a 100-partner firm billing $200M a year writes off 8-10% of fees and loses 8-10 partner hours a month to bill review. Those are vendor figures, not customer results, but every billing director recognises the pattern. A rule broken on day 1 of a matter is cheapest to fix on day 1.
• Nobody maintains 300 OCGs by hand. The current workflow is billing staff reading guideline PDFs and checking pre-bills against them. Antidote turns each OCG into a rule set automatically and keeps it next to the client’s actual payment behaviour.
• It works across time-capture tools. It does not replace iTimekeep, Intapp Time, or an AI timekeeper. It reviews whatever entries reach the system of record, so a firm with mixed capture habits gets one compliance check.

Pricing reality

Antidote publishes no prices. Sales are by demo, and Stanford’s CodeX TechIndex lists the model as a subscription. Expect an enterprise contract quoted on timekeeper count and the number of client guideline sets.

The nearest published anchor is Billables AI, whose $169/user/month Premium tier bundles capture with billing-rule checks. Our planning estimate for a compliance-only layer is $50-150 per timekeeper per month. That is an estimate, not a quote. At a 400-timekeeper firm it means roughly $240,000-720,000 a year.

The ROI test uses the firm’s own numbers. A firm billing $200M that cuts write-offs by one percentage point recovers $2M a year. Get your current write-down and e-billing rejection rate by client before the demo. Without that baseline you cannot tell whether the contract paid for itself.

Best for

Billing directors, revenue-cycle leaders, and pricing or legal ops teams at Am Law 200 firms and their UK and Australian equivalents. It fits where dozens or hundreds of institutional clients impose OCGs, and where write-downs and e-billing rejections are measured per client.

Not for firms under about 50 lawyers or firms with few guideline-driven clients. For them, a pre-bill checklist and the compliance features in their timekeeping tool cost less. Also skip it if your time-capture vendor already writes narratives to OCGs at entry and your rejection rate is low.

Alternatives and when to pick them

• Intapp Terms and Time — the large-firm incumbent, used by 96 of the Am Law 100 for conflicts and intake. Pick it when the firm already runs Intapp and wants guideline terms, time, and walls from one vendor.
• Aderant — iTimekeep, the Onyx OCG product, and the Compliance Agent check entries against client rules inside the Aderant stack. Pick it when Aderant is the billing system and you would rather extend it than add a vendor.
• PointOne — the fast-growing AI timekeeper ($16M Series A, March 2026) that writes narratives to client rules during capture and adds pre-bill review. Pick it when lost time and guideline rejections are both the problem and you want one tool for both.
• Laurel — the best-funded AI-native timekeeper ($100M Series C, June 2025). Pick it when the firm wants capture and compliance from a vendor with deeper reserves.
• Elite 3E with eBillingHub — pick it when 3E is the system of record and the firm would rather enforce billing rules where invoices are generated and submitted.

Antidote’s case against all of these is that it is capture-agnostic and does only compliance. If none fit, the interim is a policy: a one-page rule summary per top-20 client, entries reviewed weekly against it, and a partner check of the ten largest pre-bills.

Watch-outs

• SOC 2 Type 1, not Type 2, and narratives go to LLM providers. The Trust Center lists ISO/IEC 27001:2022, SOC 2 Type 1, SAML SSO, and in-region storage (EU, US, or Australia). Anthropic and Google are listed subprocessors. Some client OCGs now restrict sending matter data to AI services. Guard: before connecting the time system, request the security summary and pen-test report, confirm the data region, and check your top clients’ guidelines for AI-use clauses.
• No named integrations and no named customers. The company says it integrates with major time and practice management systems but lists none publicly. Guard: make the pilot prove it on your actual system (Aderant, Elite 3E, Intapp, or other), and ask for two reference calls at firms of your size.
• The loss figures come from the vendor. The 8-12% of billable hours lost to non-compliance is Antidote’s claim, not a measured customer result. Guard: baseline write-downs and rejections per client for the prior six months, run a 90-day pilot on five high-rejection clients, and compare.
• Email-accepted rewrites change the billing record. A one-click rewrite can shift what a narrative says about the work. Guard: keep the responsible partner’s pre-bill sign-off, and track acceptance rates per timekeeper so ignored flags surface.
• Small vendor, crowded lane. Aderant and Intapp are shipping their own compliance agents. Guard: the extracted client standards are your work product. Get written terms to export them, plus the flag history, on exit.

For the client side of the same guidelines, see outside counsel management. For the pricing side, see billable hour vs AFA.