Ellty, iDeals and Firmex are the rooms we would hand a diligence team first: reviewers find files fast, questions stay tied to documents, and the activity log holds up when someone later asks who saw what. Datasite and SmartRoom come next for very large or permission-heavy reviews.
Reviewers bill by the hour, so search, indexing and navigation directly change the cost of diligence.
Question handling
25%
Requests and answers need to stay linked to documents and visible only to the right party.
Audit evidence
25%
Disclosure disputes are settled by the activity log, so it has to be complete and exportable.
Setup effort
20%
A target company rarely has spare staff to spend a week configuring the room.
Findability for reviewers carries the most weight here: Reviewers bill by the hour, so search, indexing and navigation directly change the cost of diligence.
dataroomreview.org
Weights for this use case only; the overall ranking uses the standard weights on our how-we-test page.
A complete transaction data room with AI tools inside it and a list price on the website.
9.2/10Outstanding
Reviewers get a clean index, AI features that help them get through long documents, and a question workflow linked to the files under review. Behind that sit the same controls a seller expects from iDeals or Datasite: watermarking per viewer, download and print restrictions and a full activity history. Pricing is listed at $149/mo with a 14-day free trial.
What we liked
Every core diligence control on our checklist: routed Q&A, group permissions, viewer watermarks, print and download blocking, activity log
AI tools and signing are part of the product, not add-ons
Highest usability score in our ranking (9.8), with self-serve setup for admins
Watch out for
Neither SSO nor a public API at our last check
You redact outside the room, since there is no native tool
No native mobile app; reviewers use the mobile browser
A long-established transaction room with heavyweight security credentials and the highest service score in our ranking.
9.1/10Outstanding
iDeals handles big indexes with redaction, single sign-on and an API, and it holds the highest service score on our roster. Expect a quote rather than a list price.
What we liked
ISO 27001 and SOC 2 certified, with GDPR listed
Built-in redaction alongside watermarks and document rights control
Single sign-on and a public API for IT-led deployments
Watch out for
Pricing is quoted, so you cannot model the cost before talking to sales
No native e-signature and no AI features on our checklist
A dependable, easy-to-run room popular with mid-market dealmakers and legal teams.
8.5/10Excellent
Firmex is one of the easiest rooms for outside lawyers to learn, and it covers redaction and Q&A out of the box. It has no SSO or AI features, which most legal reviews can live without.
What we liked
Usability score of 9.0, among the best in our group
SOC 2 and ISO 27001 certified
Built-in redaction alongside watermarks and document rights control
Watch out for
No single sign-on or public API
No AI features or e-signature
Deal workflow (8.3) is a step below the enterprise rooms
The enterprise standard on banker-led sell-side deals, with ten of our twelve checklist features.
8.9/10Excellent
Datasite brings redaction, a mobile app and AI features to diligence on large auctions. You need a sales conversation to get started, as there is no self-serve trial.
What we liked
Ten of twelve checklist features, the widest coverage we track
AI features, redaction and a native mobile app
SOC 2 and ISO 27001, with GDPR listed
Watch out for
No free trial; evaluation runs through a sales demo
A US deal platform positioned around permissions, a managed question log and strict document controls.
8.2/10Very good
SmartRoom is built around detailed permission control and structured Q&A, with redaction and ISO 27001. Its interface takes longer to learn than the rooms above.
What we liked
Permissions-focused access model with document rights control
Managed question log plus redaction inside the room
Audited under SOC 2, certified to ISO 27001, with second-factor sign-in
Watch out for
Admins need real training before the first bidder logs in
Nothing to test alone and no price on the website
No AI tooling, SSO, public API, phone app or e-signature
A deal workspace that pairs a secure document room with request tracking for acquirers who buy companies regularly.
8.0/10Very good
DealRoom treats diligence as a set of tasks and requests, which suits corporate development teams running repeat acquisitions. It offers a free trial and quotes pricing.
What we liked
Request tracking and document sharing live in the same workspace
Buyer question log, viewer watermarks and limits on opened files
SOC 2 report, ISO 27001 certificate and second-factor sign-in
Watch out for
No AI tooling, single sign-on, public API or phone app
Prices in USD at the entry level; indicative, confirm with the provider.
Diligence is a reading problem
Most writing about data rooms looks at them from the seller’s chair. Diligence is the opposite seat. A buyer’s lawyers, accountants and technical advisers arrive with a request list of several hundred items and a deadline that rarely moves. Every minute spent hunting for the latest version of a supply agreement is a minute billed to the client. A room that loads slowly, buries files three folders deep or hides search behind a separate screen makes diligence more expensive, even if its licence fee looks low.
So our ranking here asks a different question from the M&A shortlist. Not “can the seller control access?” but “can a tired reviewer at eleven at night find the right file, ask a question about it and get a traceable answer?”
How the shortlist was built
We started from our six-criteria review scores and re-weighted them for a reviewing team. Findability draws on the usability and workflow criteria. Question handling looks at whether the Q&A module ties each request to a document and a user group. Audit evidence covers the depth and export of activity logs. Setup effort reflects how much configuration the target company has to do before reviewers log in. The full scoring approach sits on our review method page.
Provider
Score
Q&A
Redaction
Bulk upload
Trial
ISO 27001
Ellty
9.2
Yes
No
Yes
14 days
No (SOC 2, infrastructure)
iDeals
9.1
Yes
Yes
Yes
Yes
Yes
Firmex
8.5
Yes
Yes
Yes
Yes
Yes
Datasite
8.9
Yes
Yes
Yes
Demo only
Yes
SmartRoom
8.2
Yes
Yes
Yes
Demo only
Yes
DealRoom
8.0
Yes
No
Yes
Yes
Yes
Datasite outscores Firmex overall, yet sits below it here. The reason is setup: for a mid-sized review run by a law firm, Firmex gets reviewers working with less onboarding, and that matters more in diligence than banker-grade analytics do.
What reviewers complain about
We asked what slows down diligence in practice, and three issues come up again and again. The first is version confusion: a seller uploads a revised contract next to the old one and nobody is sure which is current. Agree a naming rule and replace files rather than duplicating them.
The second is requests that live outside the room. When a buyer’s counsel emails a question to the seller’s CFO, the answer never reaches the log. Insist that every request goes through the Q&A module, even informal ones.
The third is view-only settings applied too broadly. Reviewers who cannot download a 400-row spreadsheet end up retyping figures. Use document rights control where it matters (HR files, pricing schedules) and allow downloads elsewhere.
Personal data in the room
If employment contracts or customer files are in scope, decide early whether you will redact inside the room or before upload. Doing it after reviewers have access means the unredacted version has already been seen.
What it costs to run a diligence room
Ellty lists its entry price at $149/mo, so a four-month review starts around $600 before any add-ons. iDeals, Firmex, Datasite, SmartRoom and DealRoom quote per project. When you ask for quotes, give each vendor the same page or storage estimate, the same number of reviewer groups and the same term, otherwise the numbers will not compare. The pricing guide breaks down how those variables move the total.
Frequently asked questions
What is the best data room for due diligence?
On our scores, Ellty, iDeals and Firmex suit most diligence reviews best. All three combine fast navigation, a question workflow and a detailed activity log. Datasite and SmartRoom are strong alternatives for very large or permission-heavy reviews.
Why does the audit trail matter in diligence?
After signing, warranty and disclosure arguments often turn on whether a buyer actually had access to a document. A complete log of views and downloads per user is the evidence both sides rely on.
Is redaction necessary for a diligence room?
It helps when personal data appears in contracts or HR files. iDeals, Firmex, Datasite and SmartRoom redact inside the room. With Ellty you would redact before upload.
Can I test a diligence room before paying?
Ellty offers a 14-day free trial, and iDeals, Firmex and DealRoom offer trials too. Datasite and SmartRoom work through demos instead.
