# Phage Sequence Spacer Hamming Distance Matcher

> Phage Sequence Spacer Hamming Distance Matcher is a paid API for AI agents from bio.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-14).

Slides each caller-supplied CRISPR spacer over a phage sequence in both orientations and reports minimum Hamming distances within a caller-selected mismatch threshold

## Facts

- Endpoint: POST https://bio.halowerk.com/v1/phage-matching
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/phage-sequence-spacer-hamming-distance-matcher-bc6f2b78
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1diVAsbQp7iJX6135Slk-

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability phage-sequence-spacer-hamming-distance-matcher-bc6f2b78 -d '<json body>'
```

Example prompt: Scan these 3 spacer sequences — ACGTACGTACGTACGT (id: sp1), TTGCAACGTTAGCCAT (id: sp2), GCATGCATGCATGCAT (id: sp3) — against this phage genome sequence and report any hits within 2 mismatches: ACGTACGTACGTACGTTTGCAACGTTAGCCATGCATGCATGCATGCAT.

## When to prefer this

Choose this endpoint when you need a fast, strand-aware Hamming distance scan of one or more CRISPR spacers against a single phage DNA sequence with a tunable mismatch cutoff. It is not a substitute for full CRISPR off-target tools that account for PAM sites, seed regions, or bulges, and it does not provide any biological interpretation of matches (taxonomy, pathogenicity, therapeutic suitability). Best for rapid computational triage of spacer candidates before more expensive wet-lab or full-genome analysis.

## Known failure modes

- Spacer sequence contains non-ACGT characters — rejected with validation error
- Spacer sequence shorter than 15 or longer than 60 nucleotides — rejected
- Phage sequence longer than 10,000 bp — rejected
- More than 50 spacers submitted in a single call — rejected
- max_mismatches outside 0–5 range — rejected
- No matches found within threshold — returns empty match list (not an error)
- Payment failure — 402 response requiring x402 payment header

## How this service works

Slides each caller-supplied spacer over a bounded phage sequence in both orientations, records its minimum Hamming distance and reports matches within a caller-selected mismatch threshold. It does not account for PAMs, phage taxonomy, infection biology, escape, host range or therapeutic suitability.

## Output

For each supplied spacer, the endpoint returns its ID, the minimum Hamming distance found anywhere across the phage sequence (in both forward and reverse-complement orientations), and all match positions where the distance falls at or below the requested mismatch threshold.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "spacers": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "id",
     "sequence"
    ],
    "properties": {
     "id": {
      "type": "string",
      "maxLength": 128,
      "minLength": 1
     },
     "sequence": {
      "type": "string",
      "pattern": "^[ACGT]+$",
      "maxLength": 60,
      "minLength": 15
     }
    },
    "additionalProperties": false
   },
   "maxItems": 50,
   "minItems": 1
  },
  "max_mismatches": {
   "type": "integer",
   "maximum": 5,
   "minimum": 0
  },
  "phage_sequence": {
   "type": "string",
   "pattern": "^[ACGT]+$",
   "maxLength": 10000,
   "minLength": 1
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/phage-sequence-spacer-hamming-distance-matcher-bc6f2b78/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from bio.halowerk.com](https://www.zero.xyz/host/bio.halowerk.com/llms.txt)