---
title: "Find a non-repetitive subset of existing parts"
method: POST
path: "/nonrepetitive_parts_find"
tags: ["Enzymes & cloning"]
---

# Find a non-repetitive subset of existing parts

`POST /nonrepetitive_parts_find`

## Request

- Base URL: `https://seqbench.com/api/v1`
- URL: `https://seqbench.com/api/v1/nonrepetitive_parts_find`
- Auth: none required

Given a toolbox of genetic parts, return the largest subset in which no two parts share more than a chosen length of sequence — on either strand. Parts that share a long stretch recombine into each other in a multi-part assembly and are the single largest cause of DNA synthesis failure, and neither shows up when the parts are checked one at a time. Reports every conflicting pair and why each dropped part was dropped. Deterministic: no model, no rate, no score. Use nonrepetitive_parts_design to build new parts instead of selecting from existing ones.

## Request body

- object
  - `parts` string, required: The toolbox as (multi-)FASTA — each record's header becomes the part's name. Max 4,000 parts, 5,000 bp each.
  - `lmax` integer: Longest stretch two parts may share, in bp (default 15). Two parts conflict when they share MORE than this. Below 8 bp every pair of sequences matches by chance.
  - `bothStrands` boolean: Count a shared stretch even when one part carries it reverse-complemented. Recombination and synthesis both see both strands, so leaving this on is almost always right.
  - `strategy` '2apx' | 'greedy': Which approximation picks the subset. Maximum independent set is NP-hard, so neither is guaranteed largest: '2apx' is the standard 2-approximation, 'greedy' repeatedly drops the most-conflicting part. Try both — they disagree on real toolboxes.

## Response `200`

Tool ran successfully.

- SuccessResponse: Standard success envelope returned by every single-tool call.
  - `ok` unknown, required
  - `tool` string, required: The tool slug that ran.
  - `result` object, required: Tool-specific output object. Its shape depends on the tool — call `GET /{tool}` or see the docs for each tool's fields.
  - `gate` GateResult
    - `pass` boolean, required: True if and only if every hard check passed.
    - `checks` GateCheck[], required
      - `id` string, required
      - `label` string, required
      - `severity` 'hard' | 'soft', required
      - `pass` boolean, required
      - `message` string, required
      - `value` number
      - `threshold` string
    - `notChecked` string[], required: Honest list of what this gate does NOT verify.
  - `provenance` Provenance, required
    - `apiVersion` string, required
    - `tool` union, required: Tool slug, or an array of slugs (one per step) for a workflow.
      - string
      - string[]
    - `generatedAt` string, date-time, required: ISO 8601 timestamp of when the result was generated.

## Other responses

- `400`: Invalid argument or the tool could not run.
- `404`: Unknown tool.
- `429`: Rate limited (metered tools only). Body carries code `rate_limited` and retryable `true`; honor the Retry-After header.
- `503`: A metered tool is momentarily at capacity. The identical request should succeed after Retry-After; body carries code `upstream_unavailable`.

---

[API](https://skmtc.dev/seqbench/apis/seqbench-api.md) · [All operations](https://skmtc.dev/seqbench/apis/seqbench-api/llms.txt) · [OpenAPI document](https://skmtc.dev/seqbench/apis/seqbench-api/revisions/132575216865?raw)