mixus
mixus runs AI agents for legal work inside email, Microsoft Word and Slack. Law firms and in-house teams get .docx redlines with native track changes, live-formula financial models and analyses, with every edit approved by an attorney.
What is mixus?
mixus is an AI agent platform for legal work, published by Mixus Inc. in San Francisco, California. The name carries the thesis: mix us, human and machine intelligence combined, with organisational oversight rather than full autonomy. The About page leans on Carnegie Mellon and Salesforce findings that fully autonomous agents fail on most real business tasks, and answers with a fixed rule - the agent does the work, an attorney approves it.
The main entry point is email. You forward a matter to the agent, copy the reviewers, and the agent works inside the same thread. Three practices sit on top of that. AI Redline reads a contract in Word, PDF or any other format, picks the right playbook automatically, and returns a .docx in native track changes where every edit cites the playbook rule that triggered it, alongside a list of issues. Deal Modeling takes a term sheet and a cap table sent to agent@mixus.com and returns an .xlsx with live formulas - post-financing cap table, dilution, SAFE conversion, price-per-share and wire-amount checks - in under fifteen minutes. The Word add-in puts a native sidebar in Word Desktop and Word Online, on Mac and Windows, from Word 2016 onwards, and works alongside Litera Compare and iManage; installation is announced in under two minutes and it is included in every plan. A Slack app answers @mixus mentions in channels or direct messages.
Playbooks are the real asset: versioned rule sets scoped by client, contract type or practice area, holding opening positions, fallback positions, terms to flag and reviewer approvals. Every accept, edit or reject decision comes back as a proposed rule that a human must approve, and approved positions are reapplied automatically to similar matters.
Underneath, a multi-provider model layer draws on Anthropic, OpenAI and Google, with a vetted allowlist for redline pipelines, and AI cost is billed per run in USD with each run's duration shown. The site claims Am Law 10 firms among its users. Below the legal layer the platform stays generalist: the documentation advertises more than 200 pre-built integrations and agent creation in plain language.
What it does
- Email a contract to the agent and receive a .docx redline with native Word track changes and an issues list
- Run the firm's playbook - NDA, SaaS, MSA, employment or custom - in a single click
- Get a Series A pro forma as a live-formula .xlsx in under 15 minutes, with dilution and SAFE conversion
- Accept, edit or reject each suggestion directly inside Microsoft Word
- Mention @mixus in a Slack channel to hand off a task and get the deliverable back in the thread
- Build a playbook from the firm's past contracts and templates
- Track acceptance rates by attorney, by matter and by playbook
When to use mixus / When not to
A quick filter to help you decide if mixus is the right fit.
When to use mixus
- Law firms and in-house legal teams pushing high volumes of repetitive contracts: NDAs, MSAs, SaaS agreements, employment paperwork
- Deal teams in private equity and venture capital who need cap tables, M&A waterfalls, Series A pro formas and SAFE conversions turned around fast
- Firms that already have written review standards and want them enforced as versioned playbooks instead of tribal knowledge
- Regulated organisations that require an exportable audit trail, customer-managed encryption keys (BYOK) and a zero-retention mode
- Teams that refuse to adopt yet another interface: the work stays in Outlook or Gmail, in Word and in Slack
When not to use mixus
- Anyone expecting legal advice: mixus is not a law firm, its terms disclaim any warranty on the accuracy of AI output, and every draft still needs an attorney's review
- Mobile-first users: no iOS or Android application is published anywhere on the site
- Buyers who want public pricing before talking to sales: mixus.ai/pricing returns a 404 and the only rate card sits in the developer documentation
- Non-English-speaking teams: the interface and the documentation are available in English only
- Consumers and solo users looking for a general chatbot: the product is sold through demos and built around firm and enterprise workflows
How to use mixus
A typical end-to-end flow, from setup to results.
- Book a demo from the site: there is no open self-service sign-up on the marketing pages
- Pick a single repetitive workflow to start with - redlines, due diligence, models or extraction
- Build the playbook from the firm's past contracts and templates, then have the reviewers approve the rules
- Forward the matter to the agent by email and copy the reviewers; the agent works in the same thread
- For AI Redline, upload or email the contract in Word, PDF or any format - mixus selects the right playbook itself
- For Deal Modeling, send the term sheet and the cap table as attachments to agent@mixus.com
- Install the Word add-in from the site, or roll it out firm-wide through the Microsoft 365 Admin Center
- Add the Slack app through the OAuth link, then mention @mixus in a channel or in a direct message
- Review the returned redlines, issues and citations: reviewers need no mixus account to read the track changes
- Accept, edit or reject each change, then move to production once the playbook holds; support runs through agent@mixus.com 24/7 and support@mixus.ai for the human team
Pros & Cons
Pros
- No tool switching: the work stays in email, Word and Slack, and external reviewers need no mixus account to read the track changes
- Strong traceability: every edit in a redline cites the playbook rule that produced it, with an issues list alongside
- Real deliverables - .docx with native track changes, .xlsx with live formulas - rather than chat text to copy out
- The learning loop is explicitly gated: a proposed rule waits for human approval before it becomes firm policy
- No model lock-in: Anthropic, OpenAI and Google sit behind the same layer, with a vetted allowlist for redline pipelines
- Firm no-training commitment for mixus and its model providers alike, with the subprocessor list published by name in the privacy policy
- Controls that fit regulated work - BYOK, zero-retention mode, audit trail, US and EU data residency - and per-run AI cost in USD that makes matter-level rebilling straightforward
Cons
- No pricing page on the public site: mixus.ai/pricing returns a 404 although the terms (art. 4.1) designate it as the official source of rates
- The only rate card lives in the documentation and still prices GPT-4o, Claude 3.5 Sonnet and Gemini 1.5 Pro, which suggests the page has not been refreshed
- Compliance contradiction: the marketing site presents SOC 2 Type II and ISO 27001:2022 as obtained, while the security documentation lists both as audits in progress with October 2025 targets
- Postal address limited to San Francisco, California, with no street and no ZIP code, and no Article 27 EU representative appointed despite the EU data residency and GDPR rights on display
- No iOS or Android application, and interface and documentation in English only
- Sold through demos: no open sign-up is visible from the marketing site
- Two identities coexist - a purely legal marketing site and a generalist application with 200+ integrations and plain-language agents - with a co-founder name divergence (Elliot Glazer in the site's JSON-LD, Elliot Katz in the press) and founding years that disagree (2023 in the JSON-LD, 2024 on the Team page)
Pricing & Plans
A permanent free plan is available: Free costs 0 USD per month and includes 1,000 tokens, access to GPT-4o mini, basic web search and 5 file uploads per month. The lowest paid entry point is Pro at 20.00 USD per month, which adds 100,000 tokens, all models, unlimited uploads, priority support and the memory system. Team follows at 50 USD per month and Enterprise is quoted on request. An annual commitment applies a 20% discount to every plan while keeping the same monthly token allowances. Billing runs on the calendar month, the invoice is issued on the first day of the following month and payment is due within 15 days; usage beyond the included tokens is charged per token at model-specific rates, and included tokens do not roll over. Under the terms of service, fees are billed in advance, are non-refundable unless expressly stated or legally required, and subscriptions renew automatically, with cancellation possible at any time and access running to the end of the current period. The Word add-in is included in every plan. No time-limited free trial is announced: the permanent free plan serves that purpose. Note that this rate card is published in the documentation only, since mixus.ai/pricing returns a 404.
- 0 USD/month - 1
- 000 tokens
- GPT-4o mini
- basic web search
- 5 file uploads per month
- 20 USD/month - 100
- 000 tokens
- all models
- unlimited uploads
- priority support
- access to the memory system
- 50 USD/month - 500
- 000 tokens
- everything in Pro plus collaboration
- shared workspaces
- user management
- team analytics and SSO
- custom pricing - unlimited tokens
- everything in Team plus custom integrations
- dedicated support
- SLA
- custom deployment and advanced security
- 20% off every plan
- with the same monthly token allowances
Data, GDPR & hosting
A consolidated view of how mixus handles your data.
GDPR overview
The privacy policy updated on 22 February 2026 grants access, rectification, erasure, portability and objection, and adds for EU, UK and EEA residents the right to restrict processing and to lodge a complaint with their local supervisory authority. California residents are offered CCPA rights, with Mixus stating it sells no personal information. Requests go through support@mixus.ai or account settings, with a 30-day response commitment. Mixus Inc. is established in the United States and works with providers there and elsewhere, so transfers leave the EEA. Two gaps stand out: no Article 27 EU representative is named anywhere on the site, and no data protection officer is appointed. The homepage and Trust page present GDPR compliance as achieved, while the security documentation describes the GDPR programme as still in progress - a contradiction the publisher should settle.
Who owns the data?
Under the terms of service in force since 30 November 2025 and last revised on 22 February 2026, customers keep ownership of the content they submit and Mixus Inc. claims none of it. What the publisher takes instead is a worldwide, non-exclusive, royalty-free licence, bounded by its purpose: operating and improving the service. That licence ends when the content or the account is deleted, with three carve-outs that survive deletion - material already shared with other users, anonymised aggregate data, and backup copies kept for a reasonable period. The privacy policy, updated on 22 February 2026, applies the same logic to personal data and routes deletion requests to support@mixus.ai.
Reuse rights
The privacy policy updated on 22 February 2026 separates two streams. Declared data covers name, email address, phone number (opt-in for SMS and WhatsApp), username and support correspondence. Automatic data covers IP address, browser, operating system, device type and identifiers, usage, error logs, cookies and pixels. The stated purposes are service delivery, communication, authentication and security, payment processing, research and development, and legal compliance. Prompts, messages and documents are passed to third-party model providers - Anthropic, OpenAI and Google AI - and the publisher states that customer content is not used to train AI models. AI memory and conversation context are held in a vector database (Pinecone) that users can manage and delete from account settings. Mixus declares no behavioural advertising, no sharing with advertising partners and no sale of personal information. Subprocessors are named in the policy: Clerk for authentication, MongoDB Atlas and AWS S3 for infrastructure, Stripe for payments, Postmark for email, Twilio for SMS, PostHog for analytics and Sentry for error tracking.
Data retention & training
Hosting summary
The Trust page lists US and EU data residency among its governance controls. Mixus Inc. is established in the United States and, according to the privacy policy, runs operations and works with providers in the United States and in other countries, so data can cross borders. The declared storage stack is MongoDB Atlas and AWS S3, with Pinecone holding vector memory. Traffic is encrypted with TLS 1.3 in transit and AES-256 at rest; optional end-to-end encryption exists for enterprise customers but is not active by default. Customer-managed keys (BYOK) are available, and secrets are centrally managed with automatic rotation. Data is compartmentalised at matter level, storage is isolated per organisation, and database access is restricted by IP allowlist. Model providers operate under zero data retention, meaning prompts and outputs are not stored on their side. The domain itself resolves to 76.76.21.21, a United States address on an Amazon anycast node.
Things to keep in mind
Risks and trade-offs to weigh before adopting mixus.
- Certification contradiction: SOC 2 Type II and ISO 27001:2022 are shown as obtained on the marketing site, but listed as audits in progress with October 2025 targets in the security documentation - targets long past and never updated. Both cannot be true; confirm the status with the publisher before any regulated deployment
- GDPR and HIPAA are displayed on the homepage, while the security documentation states that the GDPR programme is still in progress, and no Article 27 EU representative is appointed despite EU data residency and GDPR rights being advertised
- AI output must be read: the terms provide the service as is and disclaim any warranty on the accuracy of AI-generated content. The reviewing attorney stays liable, and an accept-everything reflex under deadline pressure is the real risk
- Pricing opacity: mixus.ai/pricing returns a 404 although the terms designate it as the official source of rates, and the documentation rate card still prices GPT-4o, Claude 3.5 Sonnet and Gemini 1.5 Pro, so budget assumptions may not hold
- Skill erosion and measurement: when the playbook proposes and institutional memory reapplies, junior lawyers can stop building the judgement the tool depends on, while acceptance-rate analytics per attorney make individual reviewers measurable
- Identity drift across surfaces: the Word add-in is served from app.mixus.ai with a 2025 copyright and generalist messaging, while the marketing site shows a 2026 copyright and a purely legal pitch, and two agent domains are in use - agent@mixus.com and agent@mixus.ai
- Verification is hard: the postal address is limited to San Francisco, California, with no street or ZIP code, and no effective date is visible for the Trust Center commitments, whose Vanta portal renders in JavaScript and cannot be read as static content
Setup & Integrations
Technical difficulty
Low on the surface, real work underneath. Sending an email is enough to get a first result, the AI Redline page advertises no setup, the Word add-in installs in under two minutes and can be pushed firm-wide through the Microsoft 365 Admin Center, and the Slack app takes three steps with a first reply announced within three minutes. The effort sits in the playbooks: past contracts and templates must be supplied, then the resulting rules reviewed and approved. Organisation-wide SSO and MFA are configured by the mixus team on request rather than self-service, and access starts with a demo.
Deployment
Integrations
Supported languages
Behind mixus
Fundraising
Social
Resources
All the official URLs gathered for verification and reference.
Alternatives
Tools that compete with or complement mixus.
Frequently asked questions
How do I send work to the mixus agent?
What do the deliverables look like?
Is my data used to train AI models?
Which AI models does mixus use?
How much does mixus cost?
Is there a free plan or a free trial?
Does the Word add-in cost extra, and does it work with Litera and iManage?
Which security certifications does mixus hold?
Where is data hosted, and how long is it kept?
Is there a mobile app, and how do I contact support?
Should you pick mixus?
mixus makes a deliberate bet on a narrow problem: repetitive legal work, handled where it already happens, in email, in Microsoft Word and in Slack. The value is not raw model power, which mixus rents from Anthropic, OpenAI and Google alike, but the playbook and the traceability that comes with it - every edit in a redline points back to the rule that produced it, and every rule the system proposes waits for a human to approve it. Human supervision is treated as a product principle rather than a guardrail bolted on afterwards, and that is the most convincing part of the offer.
Three reservations deserve to be settled before signing. The marketing site publishes no pricing at all - /pricing returns a 404 although the terms designate it as the official source - and the only rate card sits in documentation that still prices a previous generation of models. The compliance story does not hold together: SOC 2 Type II and ISO 27001:2022 appear as obtained on the site, while the security documentation lists both as audits in progress with targets that expired in October 2025, and GDPR as a programme still under way. And no Article 27 EU representative is named, despite EU data residency and GDPR rights being advertised.
The company is young - the domain was registered in July 2024 and a USD 2.6 million pre-seed was reported in July 2025 - so a firm-wide rollout deserves the usual diligence on durability, alongside a look at the two identities the product still carries: a purely legal marketing site and a generalist agent platform in the documentation. For a firm that already has written review standards and a volume problem, mixus is worth a demo, with those questions on the list.
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