Hashtag group builder API

Paste hashtags or plain keywords in any shape. The builder adds the missing #, cuts tags at punctuation, drops duplicates and number-only tags, checks how many hashtags the network allows and splits the list into groups you can copy in one click.

• Endpoint: POST https://postboost.co/app/api/tools/hashtag-group-builder (operationId buildHashtagGroups)
• Web tool: postboost.co/tools/hashtag-group-builder
• Token: optional (limits)
• MCP: tool build-hashtag-groups on https://postboost.co/mcp/tools

Request

Field	Type	Default	Description
text	string		Hashtags or words, separated by spaces, commas or new lines. A missing # is added.
network	string: instagram, facebook, tiktok, linkedin, x, threads, bluesky, mastodon, youtube	"instagram"	Network whose hashtag cap applies.
group_size	integer		Hashtags per group. Default: the network's cap, or 5 when it has no hard cap.
case	string: keep, lower	"keep"	keep the first spelling of each hashtag, or lower-case all of them.
format	string: inline, first_comment	"inline"	inline: one line of tags. first_comment: five "." lines, then the tags.

Call it

curl

curl -X POST https://postboost.co/app/api/tools/hashtag-group-builder \
  -H 'Content-Type: application/json' \
  -d '{"text":"travel, #Travel  #travel_tips 2026 #photo!graphy"}'

Python

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

with ApiClient(Configuration()) as client:
    api = FreeToolsApi(client)
    result = api.build_hashtag_groups(FreeToolBuildHashtagGroupsRequest.from_dict({"text": "travel, #Travel  #travel_tips 2026 #photo!graphy"}))
    print(result.to_dict())

Node.js

import { FreeToolsApi } from 'postboost';

const api = new FreeToolsApi();
const { body } = await api.buildHashtagGroups({ text: "travel, #Travel  #travel_tips 2026 #photo!graphy" });
console.log(body);

PHP

use PostBoostClient\Api\FreeToolsApi;
use PostBoostClient\Model\FreeToolBuildHashtagGroupsRequest;

$api = new FreeToolsApi(new GuzzleHttp\Client());
$result = $api->buildHashtagGroups(new FreeToolBuildHashtagGroupsRequest(['text' => "travel, #Travel  #travel_tips 2026 #photo!graphy"]));
echo $result;

Go

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

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

var request postboost.FreeToolBuildHashtagGroupsRequest
if err := json.Unmarshal([]byte(`{"text":"travel, #Travel  #travel_tips 2026 #photo!graphy"}`), &request); err != nil {
    panic(err)
}

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

Ruby

require 'postboost'

api = PostBoost::FreeToolsApi.new
result = api.build_hashtag_groups(PostBoost::FreeToolBuildHashtagGroupsRequest.new({ text: "travel, #Travel  #travel_tips 2026 #photo!graphy" }))
puts result.to_hash

Java

import com.postboost.ApiClient;
import com.postboost.api.FreeToolsApi;
import com.postboost.model.FreeToolBuildHashtagGroupsRequest;
import com.postboost.model.FreeToolBuildHashtagGroupsResponse;

FreeToolsApi api = new FreeToolsApi(new ApiClient());
FreeToolBuildHashtagGroupsRequest request = FreeToolBuildHashtagGroupsRequest.fromJson("{\"text\":\"travel, #Travel  #travel_tips 2026 #photo!graphy\"}");
FreeToolBuildHashtagGroupsResponse result = api.buildHashtagGroups(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<FreeToolBuildHashtagGroupsRequest>(@"{""text"":""travel, #Travel  #travel_tips 2026 #photo!graphy""}");
var result = await api.BuildHashtagGroupsAsync(request);
Console.WriteLine(result.ToJson());

Rust

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

let config = Configuration::new();
let request: FreeToolBuildHashtagGroupsRequest = serde_json::from_str(r##"{"text":"travel, #Travel  #travel_tips 2026 #photo!graphy"}"##)?;
let result = free_tools_api::build_hashtag_groups(&config, request).await?;
println!("{:?}", result);

CLI

echo '{"text":"travel, #Travel  #travel_tips 2026 #photo!graphy"}' | ./postboost-cli --content-type application/json buildHashtagGroups -

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

Response

{
    "hashtags": [
        "#travel",
        "#travel_tips",
        "#photo"
    ],
    "removed": [
        {
            "input": "#Travel",
            "reason": "duplicate"
        },
        {
            "input": "2026",
            "reason": "digits_only"
        }
    ],
    "cap": 5,
    "group_size": 5,
    "groups": [
        {
            "tags": [
                "#travel",
                "#travel_tips",
                "#photo"
            ],
            "text": "#travel #travel_tips #photo",
            "characters": 27
        }
    ],
    "over_cap": false
}

With MCP

Connect https://postboost.co/mcp/tools (setup) and ask, for example: Clean, dedupe and split hashtags into groups that fit a network's hashtag cap with the PostBoost build-hashtag-groups 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.