gatsby-remark-find-replace

npm install --save gatsby-remark-find-replace

// In your gatsby-config.js
plugins: [
  'gatsby-plugin-sharp',
  {
    resolve: 'gatsby-transformer-remark',
    options: {
      plugins: [
        {
          resolve: 'gatsby-remark-find-replace',
          options: {
            // List your find and replace values. Both values must be strings.
            // This is required.
            replacements: {
              COMPANY: 'My Company',
              COPYRIGHT: `Copyright ${new Date().getFullYear()} My Company`,
            },

            // By default, find values are prefixed to reduce the chances of
            // conflicting with real content. You can change the prefix here.
            // Set to `false` to disable the prefix.
            prefix: '%',
          },
        },
      ],
    },
  },
]

# My Special Blog Post

Welcome to %COMPANY's new blog! Please do not copy this post.

%COPYRIGHT

# My Special Blog Post

Welcome to My Company's new blog! Please do not copy this post.

Copyright 2019 My Company