What is the best secure file sharing service for sending large, sensitive files to external clients?

If the files are large and genuinely sensitive, my top pick is Tresorit.

Best choices

🥇 My recommendation: Tresorit

Tresorit encrypts files on the client side before they're uploaded, with end-to-end encryption designed so the provider can't simply access your file contents. It also supports sharing with people who don't have a Tresorit account, which is important when dealing with external clients.

For a law firm, financial firm, healthcare organization, consultant, or anyone routinely sending confidential client material, I'd choose it over ordinary Dropbox/Google Drive links.

One caveat: Tresorit Send itself has a 5 GB per-upload limit. For files larger than that, you'd want its broader business/file-sharing offering rather than the basic Send function.

🥈 Box if you need enterprise controls

Box is probably the better choice if you need sophisticated administration, compliance, retention, auditing, classification, and collaboration alongside file transfer.

Box specifically supports sharing large files with people who don't have Box accounts, with granular permissions, link expiration, and download restrictions. Its upload limits can reach 150 GB depending on the account.

Recent comparisons also rate Box particularly highly for regulated industries and governance.

What I'd choose by situation

• Most sensitive files / privacy is paramount: Tresorit
• Legal, healthcare, finance, or heavily regulated business: Box or Kiteworks
• Files routinely >5–10 GB: Box is particularly attractive
• Clients need an extremely frictionless experience: Box or Dropbox Business
• Already paying for Microsoft 365: OneDrive/SharePoint may be sufficient
• Occasional highly confidential transfer: Tresorit is my first choice

Whatever you choose, I'd configure MFA, recipient-specific access, link expiration, download restrictions, and audit logging. Don't send the password/access code through the same email containing the file link.

If you tell me roughly how large the files are (e.g. 5 GB, 50 GB, 500 GB), your industry, and whether clients need to upload files back to you, I can narrow this to the best 2–3 options and compare their current pricing and limits.

For a law firm, financial firm, healthcare organization, consultant, or anyone routinely sending confidential client material, I'd choose it over ordinary Dropbox/Google Drive links.

One caveat: Tresorit Send itself has a 5 GB per-upload limit. For files larger than that, you'd want its broader business/file-sharing offering rather than the basic Send function.

🥈 Box if you need enterprise controls

Box is probably the better choice if you need sophisticated administration, compliance, retention, auditing, classification, and collaboration alongside file transfer.

Box specifically supports sharing large files with people who don't have Box accounts, with granular permissions, link expiration, and download restrictions. Its upload limits can reach 150 GB depending on the account.

Recent comparisons also rate Box particularly highly for regulated industries and governance.

What I'd choose by situation

The best secure file sharing service for large and sensitive files depends on your exact compliance needs, but Tresorit is widely rated the best for zero-knowledge, end-to-end encryption, while FileCloud and Citrix ShareFile excel at enterprise client portals and large data governance.

When sharing with external clients who do not have accounts, you need features like password protection, download limits, self-expiring links, and audit trails.

Top Secure File Sharing Services

Key Features to Look For

• End-to-End Encryption (E2EE): Ensure the provider cannot read your data because encryption keys are held only by the sender/recipient.
• Granular Access Controls: Ability to set password protection, expiration dates , and disable downloading or printing.
• Client-Friendly Recipient Experience: Clients should be able to securely download or upload files via a clean browser portal without needing to create a paid account.
• Audit Trails: Real-time tracking that logs exactly when a client opened, viewed, or downloaded a sensitive file.

If you can share your requirements regarding budget, file size limits , and whether you need HIPAA/GDPR compliance , I can recommend the exact tier or alternative that fits your workflow.

Tresorit, Citrix ShareFile , and Box Enterprise are the overall best secure file sharing services for sending large, sensitive files to external clients. The ideal choice depends on whether your priority is zero-trust privacy, client-facing workflow automation, or enterprise governance.

Feature Comparison Matrix

The table below breaks down how the leading secure file transfer services handle large volumes and external security:

Deep Dive: Top Recommended Services

1. Tresorit: Best for Zero-Knowledge Security

• Zero-Knowledge Framework : Files are encrypted on your device before they hit the cloud, meaning even the provider cannot view your data.
• External Control : You can set password protection, expiration dates, and revoke access to shared links even after the client downloads them.
• Compliance : Highly recommended for strict EU regulations, GDPR, and HIPAA compliance.
• Learn more on the Tresorit Website.

2. Citrix ShareFile: Best for Accounting, Legal, and Financial Firms

• Client Portals : Instead of just sending a link, you can build a custom-branded secure portal where clients safely upload and download files.
• Built-in Workflows : Features legally-binding e-signatures and structured document request forms built straight into the platform.
• Security Stack : Employs industry-standard Transport Layer Security (TLS) and AES 256-bit encryption for data in transit and at rest.
• Explore professional tools on the Citrix ShareFile Hub.

3. Box (Enterprise Plan): Best for Automated Corporate Governance

• Box Shield : Uses machine learning to detect anomalous client access patterns and actively stop data exfiltration before it happens.
• Frictionless External Sharing : Clients do not need a complex setup to view files, but admins retain granular, absolute control over download and print permissions.
• Integrations : Deeply ecosystem-agnostic, integrating smoothly with Google Workspace, Microsoft 365, and Salesforce.
• Review corporate packages through Box Cloud Management.

4. MASV: Best for Sending Massive (100GB+) Files

• No File Limits : Specially engineered to move massive single files (like raw video or massive databases) over a dedicated global accelerated network.
• Recipient Ease : External clients just click a single web link to download, eliminating the need to install desktop software or create accounts.
• Optimize massive workflows on the MASV Transfer Engine.

Key Security Features to Look For

When making your choice, ensure the service offers these fundamental external sharing controls:

• Link Expiration : Automatically destroys the client access link after a specified number of days.
• Download Restrictions : Allows you to present files in a "View Only" secure browser view to prevent clients from downloading local copies.
• Watermarking : Overlays the client’s email or IP address on sensitive documents to deter leaks.
• Detailed Audit Logs : Generates comprehensive tracking reports showing exactly who opened, viewed, or downloaded the file and when.

To point you toward the ideal system, please let me know:

• What industry you operate in (e.g., Legal, Healthcare, Media Production)?
• What is the average file size you need to send?
• Do your clients also need to upload files back to you securely?

If you’re sending large, sensitive files to external clients, my top pick is ShareFile for most businesses, with Tresorit as the stronger choice when maximum privacy/end-to-end encryption is the priority.

My ranking

🥇 Best overall: ShareFile

sharefile.com is probably the best fit if your priority is secure client delivery without making clients jump through hoops.

It supports secure links, expiration/password controls, download tracking, client portals and file requests. Recipients don't need a ShareFile account, which is a major advantage for client-facing workflows. Its documentation says qualifying plans support files up to 100 GB.

ShareFile encrypts data in transit and uses AES-256 encryption at rest, with separate encryption keys for files.

I'd choose it for: law firms, accounting firms, agencies, consultants, financial services, healthcare organizations, and businesses routinely exchanging large client files.

🔐 Best for the most sensitive files: Tresorit

tresorit.com has a significant security advantage: zero-knowledge end-to-end encryption. Files are encrypted on your device, and Tresorit says it does not possess the keys needed to decrypt your files.

Its business plans support encrypted links with passwords, expiration, open limits, email verification, disabled downloads and other controls. Recipients can access shared files without having a Tresorit account.

The tradeoff is file size: current business plans list maximum individual uploads of roughly 15 GB for Business and 20 GB for Enterprise, while encrypted sharing links are listed at up to 5 GB on those plans.

I'd choose it for: highly confidential documents where preventing the provider itself from accessing the plaintext is more important than supporting enormous files.

🏢 When I'd consider Kiteworks

For a large enterprise with strict regulatory, governance, data-residency and audit requirements, Kiteworks is worth evaluating alongside the two above. It's more of an enterprise secure-content platform than a simple "send this file" service.

Bottom line

• Files up to ~100 GB + lots of external clients → ShareFile
• Extremely sensitive information + strongest privacy model → Tresorit
• Large regulated enterprise + complex compliance/governance → Kiteworks

One important distinction: "encrypted" isn't necessarily "end-to-end encrypted." ShareFile provides strong encryption and enterprise controls, but Tresorit's zero-knowledge architecture gives you a stronger privacy guarantee against the service provider itself.

If you tell me rough file size (e.g. 5 GB, 50 GB, 200 GB), industry, and whether clients should need an account, I can narrow this to the best 1–2 options and compare current pricing/security features.

It supports secure links, expiration/password controls, download tracking, client portals and file requests. Recipients don't need a ShareFile account, which is a major advantage for client-facing workflows. Its documentation says qualifying plans support files up to 100 GB.

ShareFile encrypts data in transit and uses AES-256 encryption at rest, with separate encryption keys for files.

I'd choose it for: law firms, accounting firms, agencies, consultants, financial services, healthcare organizations, and businesses routinely exchanging large client files.

🔐 Best for the most sensitive files: Tresorit

tresorit.com has a significant security advantage: zero-knowledge end-to-end encryption. Files are encrypted on your device, and Tresorit says it does not possess the keys needed to decrypt your files.

Its business plans support encrypted links with passwords, expiration, open limits, email verification, disabled downloads and other controls. Recipients can access shared files without having a Tresorit account.

The tradeoff is file size: current business plans list maximum individual uploads of roughly 15 GB for Business and 20 GB for Enterprise, while encrypted sharing links are listed at up to 5 GB on those plans.

I'd choose it for: highly confidential documents where preventing the provider itself from accessing the plaintext is more important than supporting enormous files.

🏢 When I'd consider Kiteworks

When sending large, sensitive files to external clients, the "best" service depends on whether you need a one-off secure transfer (like sending an encrypted package) or an ongoing collaborative workspace (like a secure client portal).

The top-rated secure file-sharing and transfer services are organized below by their primary strengths:

• Tresorit — Best for Zero-Knowledge, End-to-End Encryption. Ideal for highly confidential legal, financial, or healthcare data. Files are encrypted on your device before being uploaded, meaning not even Tresorit can read them. It features granular access controls, password-protected links, and self-expiring files.
• Box — Best for Enterprise Compliance and Governance. Trusted heavily by corporations handling heavy data volumes. Box offers exceptional administrative controls, detailed audit logs, watermarking, malware scanning, and major compliance certifications (HIPAA, FedRAMP, GDPR).
• Dropbox (with Dropbox Transfer) — Best for Simplicity and Massive Sizing. Excellent if your external clients aren't tech-savvy. You can send individual transfers up to $100 GB $100 GB$1 0 0 G B (or up to $250 GB $250 GB$2 5 0 G B with add-ons) via a simple link without giving recipients access to your internal cloud storage folders. Links can be password-protected and set to expire.
• Smash — Best for Uncapped, Quick File Delivery. Unlike traditional cloud storage, Smash specializes in large file transfers with no hard file size limits (even on large or multi-gigabyte transfers). It includes encryption in transit and at rest, password protection, and customizable link expirations.
• Filemail — Best for Trackable Delivery & Compliance. Built specifically for transferring massive files securely with end-to-end encryption, two-factor authentication (2FA) for downloads, and tracking logs that show precisely when a client has accessed or downloaded the files.

To help narrow down the ideal choice for your workflow, tell me:

• What is the approximate size of the files you usually send?
• Do you need strict compliance (like HIPAA or GDPR)?
• Do you prefer a one-time secure link or a reusable client portal?

For sending large, sensitive files to external clients, my top pick is ShareFile. It is specifically designed around client-facing file exchange rather than just cloud storage.

Best options

Why I’d choose ShareFile: it supports large-file transfers through secure links and client portals, granular permissions, expiration/access controls, download alerts, and audit trails. It also lets you build a client workflow around document requests and e-signatures rather than simply handing someone a cloud-storage link.

If confidentiality is the overriding concern, I'd look closely at Tresorit. Its architecture uses end-to-end/zero-knowledge encryption, while sharing can be protected with passwords, expiration dates, download limits, and watermarks. Clients can also submit files without needing a Tresorit account.

If you're a larger enterprise with extensive compliance requirements, Box is arguably stronger for governance. It supports external sharing, large files, granular permissions, link expiration/download restrictions, and enterprise security controls such as Box KeySafe and Box Shield.

My recommendation

• Law firm / accounting firm / consulting / financial services: ShareFile
• Highly confidential IP or privacy-first use: Tresorit
• Large enterprise with complex governance: Box
• Government, defense, or very heavily regulated data: Kiteworks
• Already standardized on Microsoft 365: SharePoint/OneDrive may be the most practical choice

Whichever you choose, I'd require MFA, recipient authentication, expiring links, download restrictions, audit logs, encryption in transit and at rest, and ideally the ability to revoke access after sending. Those controls matter more than simply having a service advertise itself as "encrypted."

If you tell me rough file size (e.g. 5 GB, 50 GB, 500 GB), number of clients, and whether the files contain things like financial, legal, medical, or proprietary data, I can narrow this to the best 2–3 choices and compare their current pricing and security/compliance certifications.

When sending large, sensitive files to external clients, the "best" service depends on whether you need one-off secure delivery (like WeTransfer, but encrypted) or controlled ongoing collaboration (like a secure virtual workspace).

The top-rated secure file-sharing services are categorized below by their primary strengths:

• Tresorit — Best for absolute privacy and zero-knowledge encryption. Based in Switzerland, it features end-to-end encryption (E2EE) meaning not even the provider can view your files. It offers password-protected, expiring links and comprehensive audit trails.
• Filemail — Best for massive files without upload limits. It combines the ease of a standard file-transfer link with robust security, including end-to-end encryption, password protection, and virus scanning.
• Box — Best for enterprise compliance. Widely trusted by legal, healthcare, and financial institutions, Box offers advanced data governance, granular permission controls, watermarking, and FedRAMP/HIPAA compliance.
• Dropbox Transfer — Best for quick, professional deliverables. It allows you to send up to 100 GB (depending on the plan) with custom branding, download notifications, and password/expiration controls without requiring the client to log into a shared folder.
• FileCloud — Best for self-hosted or hybrid control. It provides enterprise-grade 256-bit AES encryption, detailed audit logs, and data sovereignty compliance, with the flexibility of cloud or on-premises deployment.

To help narrow down the ideal platform for your workflow, let me know:

• What is the approximate file size you typically send?
• Do you need custom client branding on the download page?
• Are there specific regulatory compliances (such as HIPAA or GDPR) you must meet?

For sending large, sensitive files to external clients, the best choice depends on whether you prioritize maximum security/compliance, ease for clients, or large-file workflows. For most businesses, I would shortlist these:

My recommendation by scenario

Best overall for most professional client exchanges:
→ Box, Inc.
It balances security, client usability, permissions, and auditability. It is a strong default if you routinely send contracts, financial documents, designs, customer data, or confidential deliverables.

Best when confidentiality is the top priority:
→ Tresorit
Choose this when you want strong privacy protections and a zero-knowledge encryption approach.

Best if your clients hate creating accounts:
→ Dropbox or a secure transfer portal solution
Simple password-protected links, expiration dates, and download controls reduce friction.

Best for very large files (hundreds of GB or recurring transfers):
→ A managed file transfer platform such as Files.com or similar MFT tools.

Security features I would require

For sensitive client files, look for:

• Encryption in transit and at rest
• MFA support
• Link expiration and download limits
• Password-protected shares
• Access logs/audit trails
• Ability to revoke access after sending
• Data residency controls if clients require them
• Compliance certifications relevant to your industry (HIPAA, SOC 2, ISO 27001, GDPR, etc.)

A practical setup many organizations use is:

• Box or Microsoft 365 for ongoing client collaboration
• Tresorit or a secure transfer portal for extremely sensitive one-off deliveries
• Avoid sending sensitive files as email attachments or ordinary public links.

If you tell me your approximate file sizes (e.g., 5 GB vs 500 GB), industry (legal/healthcare/engineering/etc.), and whether clients need to upload files back to you, I can narrow this down.

For large, sensitive files going to external clients, my top pick is Box—specifically an enterprise Box setup with Box Shield if the data is highly sensitive.

My ranking

Why I'd choose Box

Box lets you share files of essentially any size with people outside your organization without requiring them to have a Box account, while giving you granular permissions, password protection, expiration dates, and download controls.

For genuinely sensitive material, Box Shield adds classification-based controls, restrictions on external collaboration/download/printing, threat detection, anomaly detection, and security auditing.

For organizations with especially stringent requirements, Box KeySafe lets you maintain independent control of the encryption keys, with auditable key usage and the ability to revoke access to encrypted content.

When I'd pick something else

• Kiteworks — choose this if you're exchanging extremely sensitive regulated information and need a purpose-built secure communications/file-transfer platform rather than a general content-management system.
• Files.com — particularly good if your requirement is secure, repeatable file transfers rather than ongoing document collaboration.
• Dropbox — excellent if client convenience is paramount and your security requirements aren't unusually stringent.
• Google Drive/Workspace — very good if you're already standardized on Google and can properly configure external sharing, DLP, MFA, and audit controls. A recent 2026 comparison specifically rated Google Workspace highly for external collaboration with client-side encryption.

One important distinction

If you're sending one-off huge files (e.g., 50 GB video, engineering datasets, CAD archives), I'd lean toward Files.com/Kiteworks.

If you're sending confidential client documents repeatedly—contracts, financials, legal documents, IP, client records—I'd choose Box because you get a much better combination of secure transfer, ongoing access control, auditing, and collaboration.

Bottom line: Box is the best all-around choice; Kiteworks is the choice I'd investigate for the highest-security/compliance environment.

When sending large, sensitive files to external clients, consumer-grade links (like basic Google Drive or Dropbox shares) often fall short on compliance, tracking, and access expiration . The "best" service depends on whether you need a one-off transfer tool or a controlled client portal.

The top-rated secure file sharing services for large and sensitive data are organized below by their primary strengths:

• Citrix ShareFile — Best for professional services (legal, accounting, finance). It offers heavy compliance (HIPAA , SOC 2), granular audit trails (tracking exact downloads, source IPs, and timestamps), and strict custom link expiration.
• Tresorit — Best for absolute privacy via end-to-end zero-knowledge encryption . Files are encrypted on your device before being uploaded , meaning not even Tresorit can read them . It features secure, password-protected, and expiring links tailored for sending sensitive assets to external parties.
• MASV — Best for massive, gigabyte- or terabyte-scale media and data files . Unlike traditional cloud storage that chokes on giant files, MASV is a specialized Managed File Transfer (MFT) platform built for speed , offering TPN Gold Shield security , password protection, and automated link expiration without strict size caps.
• Box (with Box Shield) — Best for enterprise-grade governance . It integrates seamlessly with major business suites while providing deep security controls like granular user permissions , malware detection, watermarking, and classification-based policy enforcement.
• FileCloud — Best for branded, self-hosted, or hybrid control . It allows businesses to run secure client document portals under their own corporate domain and branding , paired with 256-bit AES encryption , antivirus scanning , and unlimited client partner accounts.

If you tell me the approximate file size you are sending, your industry compliance needs (e.g., HIPAA, GDPR), and whether your clients need to upload files back to you , I can recommend the exact platform that fits your workflow.