{
  "slug": "acl2",
  "name": "ACL2 (R1CS and PFCS books)",
  "tagline": "Mature prime-field constraint verification with light tactics",
  "maintainer": "ACL2 community (Kestrel Institute)",
  "url": "https://www.cs.utexas.edu/~moore/acl2/",
  "category": "provers",
  "targets": [
    "R1CS",
    "Prime-field constraint systems",
    "acl2-jolt"
  ],
  "approach": "First-order logic with strong automation; R1CS and PFCS libraries; acl2-jolt for Jolt circuits",
  "license": "Open source (BSD)",
  "status": "Mature, niche",
  "summary": "ACL2 has a mature library for R1CS and prime-field constraint systems and an acl2-jolt project. zkSecurity's 2025 comparison found it the lightest on tactic effort among circuit frameworks, at the cost of a smaller ecosystem.",
  "details": [
    "ACL2's automation suits repetitive constraint proofs; its niche status limits hiring and library reuse."
  ],
  "strengths": [
    "Least proof effort per gadget in published comparisons.",
    "Long history in hardware verification."
  ],
  "limits": [
    "Small ZK community.",
    "First-order logic limits expressiveness.",
    "Less interoperability with Lean projects."
  ],
  "fit": [
    "Consider ACL2 if you have ACL2 expertise or need to verify many similar constraint templates."
  ],
  "references": [
    [
      "zkSecurity comparison (2025-11-19)",
      "https://blog.zksecurity.xyz/posts/formal-verification-arithmetic-circuits/"
    ]
  ],
  "category_name": "Proof assistants and general verifiers",
  "page": "https://sorryfree.com/frameworks/acl2/",
  "updated": "2026-09-13"
}