8 of the Best ISO 27001 and SOC Audit Firms

Last updated: July 7, 2026

SOC 2 and ISO 27001 certifications are valuable investments that show customers they can trust your organization’s data security practices. To prove compliance, your company needs to undergo a series of intensive audits. The best ISO 27001 and SOC audit firms can help your organization meet the strict standards associated with these industry-leading cybersecurity frameworks. This guide provides an honest comparison of accredited audit firms for ISO 27001 and SOC 2 attestations, plus where a GRC platform fits in the process.

The Best ISO 27001 and SOC Audit Firms in 2026

This list rates the best audit firms from the perspective of mid-sized organizations and enterprises. Only accredited firms that offer ISO certification were considered. This guide also includes top compliance platforms that offer audit prep.

1. 360 Advanced

360 Advanced is a Florida-based CPA and compliance assessment firm covering SOC 1, SOC 2, ISO 27001, HITRUST, HIPAA, and PCI DSS engagements. Where the largest firms can make a mid-market client feel like a ticket number, 360 Advanced has built its reputation on the opposite: named engagement teams, direct access to the auditors doing the work, and findings written to be acted on rather than filed away.

That service model makes 360 Advanced an especially strong fit for growing organizations going through their first SOC 2 or ISO 27001 cycle, and for healthcare and professional services companies juggling overlapping frameworks. It’s the audit partner that still knows your name in year three.

2. Schellman

Schellman is one of the largest specialized cybersecurity assessment firms in the market, holding 14 active accreditations including ANAB accreditation as an ISO 27001 certification body. Founded in 2002, the firm has issued thousands of SOC 2 reports and hundreds of ISO 27001 certifications, and is a particular favorite of SaaS and cloud-first companies.

Schellman’s signature strength is the combined audit: a single assessor team covering SOC 2 and ISO 27001 together, cutting duplicated evidence requests and audit fatigue for organizations managing both frameworks. For companies that expect to add FedRAMP, PCI DSS, or HITRUST later, starting with a firm that holds all of those accreditations under one roof pays off.

3. Insight Assurance

Insight Assurance has a huge amount of audit expertise, with each professional bringing over 20 years of experience to the table. This isn’t surprising, considering Insight Assurance was founded by executives from the Big Four. This team has a stellar reputation for attention to detail, expert guidance, and professionalism, which explains the 97% client retention rate. Pricing sits at the premium end of this list, which is worth weighing for mid-sized businesses.

4. Mastermind

Mastermind is the modern face of the certification-body world: an audit-only firm accredited by the International Accreditation Service that focuses exclusively on information security, privacy, and responsible AI. Its certification scope covers ISO 27001, 27017, 27018, 27701, the new ISO 42001 standard for AI management systems, and CSA STAR, with assessments coordinated alongside parallel SOC 2 examinations.

Founder David Forman has also made Mastermind a teaching firm — its lead-auditor training academy is one of the more respected in the industry — and that expertise shows up in audits that explain the why behind findings, not just the what. A strong pick for cloud-first companies pursuing ISO certification with SOC 2 in parallel.

5. Coalfire Certification

Coalfire Certification does one thing and does it exceptionally well. This accredited audit firm focuses on ISO readiness assessments and certification audits only. No frills, consulting, or audit prep services mean complete impartiality. You get exactly what you pay for. If your main concerns are honesty and precision, Coalfire is an excellent choice. The certification body (recently rebranded from Coalfire ISO) is ANAB-accredited across ISO/IEC 27001, 27701, 22301, 20000-1, 9001, and the new ISO/IEC 42001 standard for AI management systems.

6. Sensiba LLP

A relative newcomer in the ISO/IEC 27001 certification space, Sensiba LLP offers an ideal balance of cost-effectiveness with experience. Sensiba LLP is mainly an accounting firm, so you can expect friendly, down-to-earth professionals who routinely work with small business owners. At the same time, the company has glowing reviews from enterprises.

7. Barr Advisory

Barr Advisory is a full-service infosec consulting firm that has a reputation for exceptional customer service. This team can help organizations at different levels of cybersecurity maturity. It’s a user-friendly choice for business owners who want ISO or SOC 2 certification but aren’t sure what steps to take next. A wide range of services includes pen testing, internal audits, compliance audits, and ISO 27001 or SOC 2 certification.

8. Consilium Labs

Consilium Labs stands out for two main reasons: Extensive cybersecurity experience and a proprietary compliance platform. This audit firm is a good fit for businesses looking for an all-in-one solution for ISO 27001 and SOC 2 compliance certification. Consilium Labs uses advanced tools for risk assessments, monitoring, readiness reviews, and audit prep.

Where Compyl Fits: Not an Audit Firm, but the Platform Behind the Audit

An important distinction before this entry: Compyl is not an audit firm and doesn’t pretend to be one. Compyl is an end-to-end GRC platform — the system organizations use to get ready for the firms on this list and stay ready between engagements. It automates evidence collection from live systems, maps a single control set across ISO 27001, SOC 2, and any other frameworks you carry, and monitors controls continuously so audit preparation stops being a three-month scramble.

So why does a platform belong on a list of audit firms? Because the audit firm and the platform are two halves of the same project: the firm issues the report or certification, and the platform determines how painful getting there is. Compyl maintains strong partnerships with leading audit firms — including firms on this list — and regularly makes introductions to match organizations with the right auditor for their industry, frameworks, and budget. When the audit starts, auditors work directly in Compyl’s auditor portal, reviewing evidence that’s already organized instead of emailing requests back and forth.

How To Choose the Best ISO and SOC Audit Firms

There are dozens — perhaps hundreds — of professional auditors in the United States, but not all have the same reputation for accuracy.

Accreditation

Choosing an accredited firm is important for certification. For SOC 2 audits, that means CPA firms backed by the American Institute of Certified Public Accountants. ISO 27001 accreditation comes from the ANAB, the ANSI National Accreditation Board. Some non-accredited auditors offer ISO 27001 “advisory” services, but they can’t provide official certification, making their audits far less valuable.

Experience

The more time and experience auditors have, the more intimately they know ISO 27001 and SOC 2 frameworks inside and out. This results in more effective recommendations that can streamline your company’s path to certification. This guide focuses on firms that have at least five to 10 years of industry experience.

Honesty

The best audit firms don’t sugarcoat things or make unrealistic promises. Instead, they provide honest feedback and a realistic list of improvements you can make in preparation for your certification audit.

Beware any auditors who offer to “get you SOC 2 ready in a few weeks.” Both ISO 27001 and SOC 2 Type II reports require extensive documentation and strong cybersecurity foundations, which take time to achieve.

Audit Quality

Beware audit firms that make it seem like their top priority is charging by the hour or finishing the job as soon as possible. Reputable auditors care about accuracy and attention to detail. They may charge more, but they tell you exactly what to expect and deliver high-quality results. 

This is where high-touch firms stand out: 360 Advanced, for example, has built its name on pairing rigorous testing with findings clients can actually act on — a useful benchmark for what audit quality should feel like.

Customer Service

Data security compliance is important for organizations of every size, from small production facilities in the DoD supply chain to global enterprises. For this reason, excellent auditors should not discount small or medium-sized businesses. Outstanding audit firms are friendly, professional, and focused on helping the client.  

Reputation

This last factor is technically a combination of the rest. Trustworthy, experienced, dedicated, and friendly auditors tend to garner top ratings from satisfied businesses. This list prioritized firms and compliance tools with at least 50 reviews and an average customer score of 4.5 stars or higher.

Costs

If it weren’t for pricing, the ‘Big Four’ accounting firms would dominate every audit list. But while some enterprises can afford to hire PwC or KPMG, not all businesses can. Many high-quality firms are more affordable for smaller businesses.

Frequently Asked Questions

Who can perform an ISO 27001 certification audit?

Only an accredited certification body can issue an ISO 27001 certificate. In the United States, accreditation comes from ANAB, the ANSI National Accreditation Board. Non-accredited firms can help you prepare, but their assessments do not result in official certification.

Who can perform a SOC 2 audit?

SOC 2 examinations must be performed by a licensed CPA firm operating under AICPA attestation standards. Many of the firms on this list are CPA firms that also hold ISO accreditations, which is what allows them to cover both frameworks.

Can the same firm audit both SOC 2 and ISO 27001?

Yes, if the firm is both a licensed CPA firm and an accredited ISO certification body. A combined audit with a single assessor team reduces duplicated evidence requests and audit fatigue, which is why multi-framework organizations often prefer firms that hold both credentials.

Do I need a GRC platform before hiring an audit firm?

It is not required, but it changes the experience. When evidence is collected automatically and organized in a platform like Compyl, auditors review what already exists instead of sending request lists, which shortens the engagement and reduces fees driven by back-and-forth.

Find the Best ISO and SOC Audit Firms for Your Business

Businesses in every industry are turning to state-of-the-art platforms like Compyl to streamline audit prep, improve compliance, visualize stakeholders, and automate workflows. This can eliminate the need to hire outside consultants for preliminary stages and lower your total expenses for the audit and certification process. At Compyl, we’re happy to help you analyze your cybersecurity maturity level and connect you with the best ISO and SOC audit firms for your needs. Contact us today.