Social media post preview API

Paste a caption and pick an image to see your post as feed cards for Instagram, X, LinkedIn and Facebook: where the text folds behind more, how each network crops the image and whether the caption fits the limit. Download any card as a PNG mockup.

• Endpoint: POST https://postboost.co/app/api/tools/social-media-post-preview (operationId previewPost)
• Web tool: postboost.co/tools/social-media-post-preview
• Token: optional (limits)
• MCP: tool preview-post on https://postboost.co/mcp/tools

Request

Field	Type	Default	Description
text	string
instagram_ratio	string: 1:1, 4:5, 1.91:1	"1:1"	Image ratio of the Instagram feed post.
image_width	integer		Image width in pixels. Give it with image_height to get display_ratio and cropped per card.
image_height	integer		Image height in pixels. Give it with image_width.

Call it

curl

curl -X POST https://postboost.co/app/api/tools/social-media-post-preview \
  -H 'Content-Type: application/json' \
  -d '{"text":"New feature: schedule a month of posts in one sitting."}'

Python

from postboost import ApiClient, Configuration
from postboost.api.free_tools_api import FreeToolsApi
from postboost.models import FreeToolPreviewPostRequest

with ApiClient(Configuration()) as client:
    api = FreeToolsApi(client)
    result = api.preview_post(FreeToolPreviewPostRequest.from_dict({"text": "New feature: schedule a month of posts in one sitting."}))
    print(result.to_dict())

Node.js

import { FreeToolsApi } from 'postboost';

const api = new FreeToolsApi();
const { body } = await api.previewPost({ text: "New feature: schedule a month of posts in one sitting." });
console.log(body);

PHP

use PostBoostClient\Api\FreeToolsApi;
use PostBoostClient\Model\FreeToolPreviewPostRequest;

$api = new FreeToolsApi(new GuzzleHttp\Client());
$result = $api->previewPost(new FreeToolPreviewPostRequest(['text' => "New feature: schedule a month of posts in one sitting."]));
echo $result;

Go

import (
    "context"
    "encoding/json"
    "fmt"

    postboost "github.com/postboost-co/postboost-go"
)

var request postboost.FreeToolPreviewPostRequest
if err := json.Unmarshal([]byte(`{"text":"New feature: schedule a month of posts in one sitting."}`), &request); err != nil {
    panic(err)
}

client := postboost.NewAPIClient(postboost.NewConfiguration())
result, _, err := client.FreeToolsAPI.PreviewPost(context.Background()).FreeToolPreviewPostRequest(request).Execute()
fmt.Println(result, err)

Ruby

require 'postboost'

api = PostBoost::FreeToolsApi.new
result = api.preview_post(PostBoost::FreeToolPreviewPostRequest.new({ text: "New feature: schedule a month of posts in one sitting." }))
puts result.to_hash

Java

import com.postboost.ApiClient;
import com.postboost.api.FreeToolsApi;
import com.postboost.model.FreeToolPreviewPostRequest;
import com.postboost.model.FreeToolPreviewPostResponse;

FreeToolsApi api = new FreeToolsApi(new ApiClient());
FreeToolPreviewPostRequest request = FreeToolPreviewPostRequest.fromJson("{\"text\":\"New feature: schedule a month of posts in one sitting.\"}");
FreeToolPreviewPostResponse result = api.previewPost(request);
System.out.println(result.toJson());

C#

using Newtonsoft.Json;
using PostBoost.Client.Api;
using PostBoost.Client.Client;
using PostBoost.Client.Model;

var api = new FreeToolsApi(new Configuration());
var request = JsonConvert.DeserializeObject<FreeToolPreviewPostRequest>(@"{""text"":""New feature: schedule a month of posts in one sitting.""}");
var result = await api.PreviewPostAsync(request);
Console.WriteLine(result.ToJson());

Rust

use postboost::apis::configuration::Configuration;
use postboost::apis::free_tools_api;
use postboost::models::FreeToolPreviewPostRequest;

let config = Configuration::new();
let request: FreeToolPreviewPostRequest = serde_json::from_str(r##"{"text":"New feature: schedule a month of posts in one sitting."}"##)?;
let result = free_tools_api::preview_post(&config, request).await?;
println!("{:?}", result);

CLI

echo '{"text":"New feature: schedule a month of posts in one sitting."}' | ./postboost-cli --content-type application/json previewPost -

With a token, send Authorization: Bearer YOUR_API_TOKEN as a default header (how, per SDK).

Response

{
    "networks": [
        {
            "key": "instagram",
            "count": 54,
            "limit": 2200,
            "over": false,
            "preview": "New feature: schedule a month of posts in one sitting.",
            "folded": false,
            "min_ratio": "1:1",
            "max_ratio": "1:1"
        },
        {
            "key": "x",
            "count": 54,
            "limit": 280,
            "over": false,
            "preview": "New feature: schedule a month of posts in one sitting.",
            "folded": false,
            "min_ratio": "4:5",
            "max_ratio": "2:1"
        },
        {
            "key": "linkedin",
            "count": 54,
            "limit": 3000,
            "over": false,
            "preview": "New feature: schedule a month of posts in one sitting.",
            "folded": false,
            "min_ratio": "4:5",
            "max_ratio": "1.91:1"
        },
        {
            "key": "facebook",
            "count": 54,
            "limit": 5000,
            "over": false,
            "preview": "New feature: schedule a month of posts in one sitting.",
            "folded": false,
            "min_ratio": "4:5",
            "max_ratio": "1.91:1"
        }
    ]
}

With MCP

Connect https://postboost.co/mcp/tools (setup) and ask, for example: Preview where a post folds and when its image is cropped on Instagram, X, LinkedIn and Facebook with the PostBoost preview-post tool.

Errors

Status	When
401	The Authorization header holds an invalid token. Leave it out to call as a guest.
413	The JSON body is larger than 128 KB.
422	A field is invalid; the body lists the errors per field.
429	A limit is reached; see limits.