> ## Documentation Index > Fetch the complete documentation index at: https://docs.aflux.ai/llms.txt > Use this file to discover all available pages before exploring further. # Post apiv1campaignsad copyvalidate > Checks a marked-up ad text against exactly the rules campaign creation will apply to it, and answers with everything that is wrong rather than the first problem found. The WYSIWYG editor on the front end serialises its state into our markup and calls this on every pause in typing: there is no second parser anywhere, so this endpoint and campaign creation cannot disagree by construction. A text that is wrong is still a successful call — the verdict is in the body, and a 4xx here means the request itself was malformed (an unusable destinationUrl, a missing field). ## OpenAPI ````yaml https://backend.aflux.ai/openapi post /api/v1/campaigns/ad-copy/validate openapi: 3.0.3 info: title: AdFlux Backend API version: v1 servers: - url: / security: [] tags: - name: auth - name: users - name: uploads - name: projects - name: campaigns - name: placements - name: billing - name: payments - name: image-generations paths: /api/v1/campaigns/ad-copy/validate: post: tags: - campaigns description: >- Checks a marked-up ad text against exactly the rules campaign creation will apply to it, and answers with everything that is wrong rather than the first problem found. The WYSIWYG editor on the front end serialises its state into our markup and calls this on every pause in typing: there is no second parser anywhere, so this endpoint and campaign creation cannot disagree by construction. A text that is wrong is still a successful call — the verdict is in the body, and a 4xx here means the request itself was malformed (an unusable destinationUrl, a missing field). operationId: campaignsValidateAdCopy requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/ValidateAdCopyRequest' responses: '200': description: Success content: application/json: schema: $ref: '#/components/schemas/ValidateAdCopyResponse' default: $ref: '#/components/responses/DefaultError' security: - Bearer: [] components: schemas: ValidateAdCopyRequest: type: object required: - text - destinationUrl properties: text: type: string maxLength: 8000 description: >- The ad text as the advertiser wrote it, markup included. Formatting is written the way Telegram writes it — *bold*, _italic_, __underline__, ~strikethrough~, ||spoiler||, `monospace`, >quote to the end of the line — plus two of ours: `--` becomes an em dash, and {these words} become the post's link to destinationUrl. A premium custom emoji is written `![😀](tg://emoji?id=5368324170671202286)`: the emoji with that document id is drawn over the character in the brackets, which has to be a single emoji itself — it is what a reader whose client cannot resolve the id goes on seeing, and it is what the visible length counts. Only the ten characters that mean something need escaping (\* \_ \~ \` \| \{ \} \> \- \\); full stops, brackets and percent signs are plain text, unlike Bot API MarkdownV2. An exclamation mark is plain text too, everywhere except in front of a `[`, where it would begin the custom-emoji form: `\!` there is the character itself, and it is how a text carrying `![😀](tg://emoji?id=...)` as literal characters is written down. Inside a recognised web address none of them mean anything at all: `mysite.com/my_page_2` keeps both underscores, `/a--b` keeps both hyphens and `?utm_campaign={campaign}` keeps its braces, so nobody has to escape his own URL. The cap here is a bound on work per request, an order of magnitude above any text that could pass the 700-character visible limit; exceeding it is a 400, not a validation error. destinationUrl: type: string minLength: 1 maxLength: 2048 description: >- Where the campaign's link goes. Required because it is what defines the advertiser's own domain, and the rule that no other domain may appear in the text cannot be evaluated without it. Accepted with or without a scheme while the advertiser is still typing the form field; anything that is not a URL either way is a 400. ValidateAdCopyResponse: type: object required: - valid - visibleLength - errors properties: valid: type: boolean description: >- True only when errors is empty. Campaign creation will accept exactly the texts this is true for visibleLength: type: integer format: int32 description: >- Length of what the reader will see — markup characters removed, `--` already an em dash — counted in UTF-16 code units, so an emoji counts as 2. This is the number the 700 limit applies to and the number an editor should put in its character counter errors: type: array items: $ref: '#/components/schemas/AdCopyError' AdCopyError: type: object required: - offset - length - code - message description: >- One problem, positioned so an editor can underline it. offset and length address the marked-up string that was sent, NOT the visible text, because that is where the mistake is: the visible text does not contain the '*' that was never closed. Both are in UTF-16 code units. properties: offset: type: integer format: int32 length: type: integer format: int32 code: $ref: '#/components/schemas/AdCopyErrorCode' message: type: string description: >- English prose for a human. Branch on code, never on this — the wording is free to change ErrorResponse: type: object required: - error properties: error: type: string AdCopyErrorCode: type: string description: >- UNCLOSED_ENTITY - a delimiter was opened and the text ended first. AMBIGUOUS_DELIMITER - '___', which is '__'+'_' or '_'+'__' with nothing to choose between them. OVERLAPPING_ENTITIES - a closer belongs to a section that is not the innermost open one; styles must nest. EMPTY_ENTITY - a delimiter pair with nothing between it. EMPTY_LINK - '{}' with no anchor text. INVALID_ESCAPE - a backslash before a character that is not escapable. NESTED_LINK - '{' inside another '{...}'. UNMATCHED_LINK_CLOSE - '}' with no '{' open. INVALID_CUSTOM_EMOJI_FALLBACK - the '[x]' of '![x](tg://emoji?id=...)' is not a single emoji. The custom emoji is drawn over that character, and every reader whose client cannot resolve it goes on seeing exactly what stands there, so a letter, a digit, a word, a space or nothing at all is refused. INVALID_CUSTOM_EMOJI_ID - the id of '![x](tg://emoji?id=...)' is not an unsigned whole number that fits in 64 bits. LINK_REQUIRED - the text contains no '{...}' at all. FOREIGN_LINK - a URL or domain that is not the advertiser's own or a subdomain of it. TEXT_TOO_LONG - the visible text is over 700 units. enum: - UNCLOSED_ENTITY - AMBIGUOUS_DELIMITER - OVERLAPPING_ENTITIES - EMPTY_ENTITY - EMPTY_LINK - INVALID_ESCAPE - NESTED_LINK - UNMATCHED_LINK_CLOSE - INVALID_CUSTOM_EMOJI_FALLBACK - INVALID_CUSTOM_EMOJI_ID - LINK_REQUIRED - FOREIGN_LINK - TEXT_TOO_LONG responses: DefaultError: description: Error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' securitySchemes: Bearer: type: http scheme: bearer bearerFormat: JWT ````