---
title: "Golden Gate overhang set designer"
method: POST
path: "/golden_gate_design"
tags: ["Enzymes & cloning"]
---

# Golden Gate overhang set designer

`POST /golden_gate_design`

## Request

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

CHOOSE a set of 4-base Golden Gate/MoClo junction overhangs, rather than scoring one you already have. Maximizes the fidelity of the set's WEAKEST junction against the same published T4-ligase ligation data golden_gate_fidelity scores with, subject to every member actually ligating well — an overhang can score a perfect ratio simply because nothing was ever measured cross-reacting with it, and 94% of the ligation matrix is zeros. Pin the overhangs your vector already commits you to with `fixed`, forbid others with `forbidden`, and give `junctions` when the junctions sit at real positions in real sequence and may only slide a few bases. Reports whether the search was exhaustive (provably the best available) or budget-limited (the best found).

## Request body

- object
  - `count` integer, required: How many junctions the assembly has, INCLUDING any given in `fixed`.
  - `fixed` string[]: Overhangs that must appear — typically the ones the destination vector already commits you to. Scored like any other member; simply not swappable.
  - `forbidden` string[]: Overhangs the design may not use, whatever they score.
  - `junctions` object[]: One entry per junction still to be chosen, as {sequence, position, slide}: the construct sequence, the 1-based first base of the preferred overhang, and how many bases either side the junction may move. Use this instead of a free design when the junctions are real places in real DNA — the candidates then come from bases that actually exist. Length must equal count minus fixed.
  - `dataset` 'generic-t4-37c-1h' | 'bsai-hfv2': Which real ligation dataset to optimize against.
  - `minCorrectSignal` number: Reject any overhang whose own correct-join signal is below this. Defaults to the chosen dataset's MEDIAN diagonal (2,694 for generic T4, 520 for BsaI-HFv2 — they differ five-fold, which is why this is derived rather than fixed). Set 0 to allow every overhang.

## 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)