Best ISO 27001 Auditors: 29 Firms Compared
ISO 27001 certification must come from an accredited certification body, and many teams pair it with SOC 2 to cover both markets. The 29 firms below have ISO 27001 work on record in the AuditNex directory — compare their profiles before you shortlist.
Top 10 ISO 27001 audit firms, ranked
Select up to three firms below to compare them side by side.
1. A-LIGN
Unverified · public records- – Price band: not yet verified
- – Typical timeline: not yet verified
- ✓ GRC integrations on record: Drata, Secureframe, Vanta
- ✓ CPA firm (attestation-capable)
- – No verified client reviews yet
2. Aprio
Unverified · public records- – Price band: not yet verified
- – Typical timeline: not yet verified
- ✓ GRC integrations on record: Drata, Vanta
- ✓ CPA firm (attestation-capable)
- – No verified client reviews yet
3. BARR Advisory
Unverified · public records- – Price band: not yet verified
- – Typical timeline: not yet verified
- ✓ GRC integrations on record: Drata, Secureframe, Vanta
- ✓ CPA firm (attestation-capable)
- – No verified client reviews yet
4. Insight Assurance
Unverified · public records- – Price band: not yet verified
- – Typical timeline: not yet verified
- ✓ GRC integrations on record: Drata, Secureframe, Vanta
- ✓ CPA firm (attestation-capable)
- – No verified client reviews yet
5. Prescient Assurance
Unverified · public records- – Price band: not yet verified
- – Typical timeline: not yet verified
- ✓ GRC integrations on record: Drata, Secureframe, Vanta
- ✓ CPA firm (attestation-capable)
- – No verified client reviews yet
6. Schellman
Unverified · public records- – Price band: not yet verified
- – Typical timeline: not yet verified
- ✓ GRC integrations on record: Drata, Secureframe, Vanta
- ✓ CPA firm (attestation-capable)
- – No verified client reviews yet
7. Sensiba
Unverified · public records- – Price band: not yet verified
- – Typical timeline: not yet verified
- ✓ GRC integrations on record: Drata, Vanta
- ✓ CPA firm (attestation-capable)
- – No verified client reviews yet
8. 360 Advanced
Unverified · public records- – Price band: not yet verified
- – Typical timeline: not yet verified
- – GRC integrations: not yet verified
- ✓ CPA firm (attestation-capable)
- – No verified client reviews yet
9. Baker Tilly
Unverified · public records- – Price band: not yet verified
- – Typical timeline: not yet verified
- – GRC integrations: not yet verified
- ✓ CPA firm (attestation-capable)
- – No verified client reviews yet
10. BDO USA
Unverified · public records- – Price band: not yet verified
- – Typical timeline: not yet verified
- – GRC integrations: not yet verified
- ✓ CPA firm (attestation-capable)
- – No verified client reviews yet
Compare at a glance
| # | Firm | Price band | Timeline | GRC platforms | Verified reviews | Status |
|---|---|---|---|---|---|---|
| 1 | A-LIGN | Not yet verified | Not yet verified | Drata, Secureframe, Vanta | No verified reviews yet | Unverified |
| 2 | Aprio | Not yet verified | Not yet verified | Drata, Vanta | No verified reviews yet | Unverified |
| 3 | BARR Advisory | Not yet verified | Not yet verified | Drata, Secureframe, Vanta | No verified reviews yet | Unverified |
| 4 | Insight Assurance | Not yet verified | Not yet verified | Drata, Secureframe, Vanta | No verified reviews yet | Unverified |
| 5 | Prescient Assurance | Not yet verified | Not yet verified | Drata, Secureframe, Vanta | No verified reviews yet | Unverified |
| 6 | Schellman | Not yet verified | Not yet verified | Drata, Secureframe, Vanta | No verified reviews yet | Unverified |
| 7 | Sensiba | Not yet verified | Not yet verified | Drata, Vanta | No verified reviews yet | Unverified |
| 8 | 360 Advanced | Not yet verified | Not yet verified | Not yet verified | No verified reviews yet | Unverified |
| 9 | Baker Tilly | Not yet verified | Not yet verified | Not yet verified | No verified reviews yet | Unverified |
| 10 | BDO USA | Not yet verified | Not yet verified | Not yet verified | No verified reviews yet | Unverified |
What to check before hiring an ISO 27001 auditor
Accredited certification body
Only an accredited certification body (e.g. ANAB or UKAS accredited) can issue the ISO 27001 certificate. Confirm accreditation and scope.
Stage 1 + Stage 2 plan
A credible auditor lays out both stages, the surveillance audit cadence, and the three-year recertification cycle up front.
SOC 2 crossover
If you also need SOC 2, a firm that handles both can reuse evidence and cut total audit effort significantly.
Sector experience
ISMS scoping differs a lot between SaaS, fintech, and hardware companies — ask for relevant certificates issued.
Frequently asked questions
Who can issue an ISO 27001 certificate?
Only an accredited certification body can issue an ISO 27001 certificate. Many audit firms also offer readiness assessments and internal audits, but the certificate itself must come from an accredited body — always confirm accreditation and its scope.
Can one firm do both my SOC 2 and ISO 27001?
Often yes. Many CPA firms with ISO 27001 practices (or certification-body partnerships) can run both engagements and reuse overlapping evidence, which typically lowers total cost and audit fatigue.
How were these ISO 27001 firms ranked?
By verification status, then profile completeness, then verified client reviews. AuditNex does not accept payment for placement; the methodology page documents every ranking signal.
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