API reference

Structure drawings

2D structure and reaction drawings (SVG) from SMILES and reaction SMILES, drawn on CogniChem servers. Free; structures are not sent to other services.

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Draw 2D structures from SMILES

POST/api/v1/depict

API key or token

SVG drawings for up to 20 SMILES, in request order. A SMILES that cannot be drawn returns svg: null with an error code instead of failing the request. Structures are drawn on CogniChem servers and never sent to another service.

Request body

application/json · DepictRequest

Request fields
Field	Type	Description
`height`	`integer`	Pixels. Default: `220`Limits: `≥ 100, ≤ 600`
`smiles[]`required	`string[]`	Up to 20 SMILES (each 1-1000 characters). Limits: `min items 1, max items 20`
`width`	`integer`	Pixels. Default: `300`Limits: `≥ 100, ≤ 600`

Example request

curl -X POST "https://api.cognichem.com/api/v1/depict" \
  -H "X-Api-Key: $COGNICHEM_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "height": 220,
  "smiles": [
    "CC(=O)Oc1ccccc1C(=O)O"
  ],
  "width": 300
}'

import os

import httpx

response = httpx.post(
    "https://api.cognichem.com/api/v1/depict",
    headers={"X-Api-Key": os.environ["COGNICHEM_API_KEY"]},
    json={
        "height": 220,
        "smiles": ["CC(=O)Oc1ccccc1C(=O)O"],
        "width": 300,
    },
)
response.raise_for_status()
print(response.json())

Uses httpx; the Python SDK has no method for this endpoint.

Responses

Successful Response · application/json · DepictResponse

Response fields
Field	Type	Description
`items[]`required	`Depiction[]`
items.`error`	`string \| null`	unparseable: not valid SMILES (or reaction SMILES). too_large: more than 200 heavy atoms (in the whole reaction). render_failed: the structure could not be laid out. One of: `"unparseable", "too_large", "render_failed"`
items.`svg`	`string \| null`	SVG document with a transparent background.

Example 200 response

{
  "items": [
    {
      "svg": "<?xml version='1.0' encoding='iso-8859-1'?>\n<svg version='1.1' …</svg>"
    },
    {
      "error": "unparseable"
    }
  ]
}

Errors are RFC 7807 problem details (application/problem+json) with status, title, detail, request_id, and a retryability hint (validation, auth, quota, conflict, upstream, timeout, or terminal). Handling errors

Error statuses
Status	When
`400`	Invalid input or business rule violation.
`401`	Missing or invalid credentials.
`402`	Wallet cannot cover the Assistant turn hold.
`403`	Authenticated but not allowed to access the resource.
`404`	Resource not found or not owned by the user.
`409`	Conflict (e.g. idempotency key reuse with a different body).
`413`	Request body or workflow spec exceeds size caps.
`422`	Request body or query failed validation.
`429`	Rate limit exceeded.
`500`	Unexpected server error.
`503`	Dependency temporarily unavailable.

Draw reactions from reaction SMILES

POST/api/v1/depict/reactions