---
title: "Evaluate ad-hoc expression"
method: POST
path: "/"
tags: ["Evaluation"]
---

# Evaluate ad-hoc expression

`POST /`

Evaluate an ad-hoc FUME expression. The request body can be a JSON object with `fume` (required), `input`, and `contentType` fields.

## Query parameters

- `verbose` string

## Request body

- object
  - `fume` string, required — FUME expression to evaluate
  - `input` unknown
  - `contentType` string — Content type for input conversion

## Response `200`

Evaluation result

- unknown

## Other responses

- `206` — Partial evaluation result
- `400` — Missing or empty `fume` expression
- `415` — Unsupported media type
- `422` — Expression compilation or evaluation error

## Changes

- **2026-07-17** `38d0cabbc2ce` — 6 warning, 6 info
  - removed the optional property `diagnostics/debug/items/instanceOf` from the response with the `206` status
  - removed the optional property `diagnostics/error/items/instanceOf` from the response with the `206` status
  - removed the optional property `diagnostics/warning/items/instanceOf` from the response with the `206` status
  - removed the optional property `oneOf[#/components/schemas/VerboseReport]/diagnostics/debug/items/instanceOf` from the response with the `415` status
  - …8 more
- **2026-02-17** `be37a3a52636` — 2 breaking
  - removed the enum value `1` from the `query` request parameter `verbose`
  - removed the enum value `true` from the `query` request parameter `verbose`
- **2026-02-17** `de8a090b44bf` — 6 breaking
  - response property `line` list-of-types was widened by adding types `string` to media type `application/json` of response `400`
  - response property `line` list-of-types was widened by adding types `string` to media type `application/json` of response `422`
  - response property `position` list-of-types was widened by adding types `string` to media type `application/json` of response `400`
  - response property `position` list-of-types was widened by adding types `string` to media type `application/json` of response `422`
  - …2 more
- …earlier changes not shown

[Full history](https://skmtc.dev/outburn-il/apis/fume-community-api/changes/post.md)

---

[API](https://skmtc.dev/outburn-il/apis/fume-community-api.md) · [All operations](https://skmtc.dev/outburn-il/apis/fume-community-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/outburn-il/fume-community-api/revisions/38d0cabbc2ce/schema)