diff --git a/runtime/doc/api.txt b/runtime/doc/api.txt
index f37d349fd8..90c9d0ccbb 100644
--- a/runtime/doc/api.txt
+++ b/runtime/doc/api.txt
@@ -2783,6 +2783,9 @@ nvim_buf_set_extmark({buffer}, {ns_id}, {line}, {col}, {*opts})
                     drawn by a UI. When set, the UI will receive win_extmark
                     events. Note: the mark is positioned by virt_text
                     attributes. Can be used together with virt_text.
+                  • url: A URL to associate with this extmark. In the TUI, the
+                    OSC 8 control sequence is used to generate a clickable
+                    hyperlink to this URL.
 
     Return: ~
         Id of the created/updated extmark
diff --git a/runtime/doc/news.txt b/runtime/doc/news.txt
index d63d1e6928..a7c4e8147c 100644
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -301,6 +301,10 @@ The following new APIs and features were added.
 
 • |vim.version.le()| and |vim.version.ge()| are added to |vim.version|.
 
+• |extmarks| can be associated with a URL and URLs are included as a new
+  highlight attribute. The TUI will display URLs using the OSC 8 control
+  sequence, enabling clickable text in supporting terminals.
+
 ==============================================================================
 CHANGED FEATURES                                                 *news-changed*
 
diff --git a/runtime/doc/ui.txt b/runtime/doc/ui.txt
index c81420d1f2..b8d47923ca 100644
--- a/runtime/doc/ui.txt
+++ b/runtime/doc/ui.txt
@@ -328,9 +328,11 @@ numerical highlight ids to the actual attributes.
 	`underdotted`:		underdotted text. The dots have `special` color.
 	`underdashed`:		underdashed text. The dashes have `special` color.
 	`altfont`:		alternative font.
-	`blend`:		Blend level (0-100). Could be used by UIs to
+	`blend`:		blend level (0-100). Could be used by UIs to
 				support blending floating windows to the
 				background or to signal a transparent cursor.
+	`url`:			a URL associated with this highlight. UIs can
+				display this URL however they wish.
 
 	For absent color keys the default color should be used. Don't store
 	the default value in the table, rather a sentinel value, so that
diff --git a/runtime/lua/vim/_meta/api.lua b/runtime/lua/vim/_meta/api.lua
index f773ddd75c..076aae7dbe 100644
--- a/runtime/lua/vim/_meta/api.lua
+++ b/runtime/lua/vim/_meta/api.lua
@@ -607,6 +607,9 @@ function vim.api.nvim_buf_line_count(buffer) end
 ---                 drawn by a UI. When set, the UI will receive win_extmark
 ---                 events. Note: the mark is positioned by virt_text
 ---                 attributes. Can be used together with virt_text.
+---               • url: A URL to associate with this extmark. In the TUI, the
+---                 OSC 8 control sequence is used to generate a clickable
+---                 hyperlink to this URL.
 --- @return integer
 function vim.api.nvim_buf_set_extmark(buffer, ns_id, line, col, opts) end
 
diff --git a/runtime/lua/vim/_meta/api_keysets.lua b/runtime/lua/vim/_meta/api_keysets.lua
index 5ebedc977b..00d3ff5bb4 100644
--- a/runtime/lua/vim/_meta/api_keysets.lua
+++ b/runtime/lua/vim/_meta/api_keysets.lua
@@ -192,6 +192,7 @@ error('Cannot require a meta file')
 --- @field fg_indexed? boolean
 --- @field bg_indexed? boolean
 --- @field force? boolean
+--- @field url? string
 
 --- @class vim.api.keyset.highlight_cterm
 --- @field bold? boolean
@@ -272,6 +273,7 @@ error('Cannot require a meta file')
 --- @field spell? boolean
 --- @field ui_watched? boolean
 --- @field undo_restore? boolean
+--- @field url? string
 
 --- @class vim.api.keyset.user_command
 --- @field addr? any
diff --git a/src/nvim/api/extmark.c b/src/nvim/api/extmark.c
index 1f0e867162..27a4b7854f 100644
--- a/src/nvim/api/extmark.c
+++ b/src/nvim/api/extmark.c
@@ -481,6 +481,8 @@ Array nvim_buf_get_extmarks(Buffer buffer, Integer ns_id, Object start, Object e
 ///                   by a UI. When set, the UI will receive win_extmark events.
 ///                   Note: the mark is positioned by virt_text attributes. Can be
 ///                   used together with virt_text.
+///               - url: A URL to associate with this extmark. In the TUI, the OSC 8 control
+///                   sequence is used to generate a clickable hyperlink to this URL.
 ///
 /// @param[out]  err   Error details, if any
 /// @return Id of the created/updated extmark
@@ -494,6 +496,7 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
   DecorSignHighlight sign = DECOR_SIGN_HIGHLIGHT_INIT;
   DecorVirtText virt_text = DECOR_VIRT_TEXT_INIT;
   DecorVirtText virt_lines = DECOR_VIRT_LINES_INIT;
+  char *url = NULL;
   bool has_hl = false;
 
   buf_T *buf = find_buffer_by_handle(buffer, err);
@@ -678,6 +681,10 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
     has_hl = true;
   }
 
+  if (HAS_KEY(opts, set_extmark, url)) {
+    url = string_to_cstr(opts->url);
+  }
+
   if (opts->ui_watched) {
     hl.flags |= kSHUIWatched;
     if (virt_text.pos == kVPosOverlay) {
@@ -747,6 +754,11 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
     if (kv_size(virt_lines.data.virt_lines)) {
       decor_range_add_virt(&decor_state, r, c, line2, col2, decor_put_vt(virt_lines, NULL), true);
     }
+    if (url != NULL) {
+      DecorSignHighlight sh = DECOR_SIGN_HIGHLIGHT_INIT;
+      sh.url = url;
+      decor_range_add_sh(&decor_state, r, c, line2, col2, &sh, true, 0, 0);
+    }
     if (has_hl) {
       DecorSignHighlight sh = decor_sh_from_inline(hl);
       decor_range_add_sh(&decor_state, r, c, line2, col2, &sh, true, (uint32_t)ns_id, id);
@@ -772,7 +784,14 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
     }
 
     uint32_t decor_indexed = DECOR_ID_INVALID;
+    if (url != NULL) {
+      DecorSignHighlight sh = DECOR_SIGN_HIGHLIGHT_INIT;
+      sh.url = url;
+      sh.next = decor_indexed;
+      decor_indexed = decor_put_sh(sh);
+    }
     if (sign.flags & kSHIsSign) {
+      sign.next = decor_indexed;
       decor_indexed = decor_put_sh(sign);
       if (sign.text[0]) {
         decor_flags |= MT_FLAG_DECOR_SIGNTEXT;
@@ -814,6 +833,10 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
 error:
   clear_virttext(&virt_text.data.virt_text);
   clear_virtlines(&virt_lines.data.virt_lines);
+  if (url != NULL) {
+    xfree(url);
+  }
+
   return 0;
 }
 
diff --git a/src/nvim/api/keysets_defs.h b/src/nvim/api/keysets_defs.h
index b2f0039eb9..811f60f4d6 100644
--- a/src/nvim/api/keysets_defs.h
+++ b/src/nvim/api/keysets_defs.h
@@ -54,6 +54,7 @@ typedef struct {
   Boolean spell;
   Boolean ui_watched;
   Boolean undo_restore;
+  String url;
 } Dict(set_extmark);
 
 typedef struct {
@@ -183,6 +184,7 @@ typedef struct {
   Boolean fg_indexed;
   Boolean bg_indexed;
   Boolean force;
+  String url;
 } Dict(highlight);
 
 typedef struct {
diff --git a/src/nvim/api/ui.c b/src/nvim/api/ui.c
index b42c274411..f955b315a8 100644
--- a/src/nvim/api/ui.c
+++ b/src/nvim/api/ui.c
@@ -784,6 +784,14 @@ void remote_ui_hl_attr_define(UI *ui, Integer id, HlAttrs rgb_attrs, HlAttrs cte
   MAXSIZE_TEMP_DICT(cterm, HLATTRS_DICT_SIZE);
   hlattrs2dict(&rgb, NULL, rgb_attrs, true, false);
   hlattrs2dict(&cterm, NULL, rgb_attrs, false, false);
+
+  // URLs are not added in hlattrs2dict since they are used only by UIs and not by the highlight
+  // system. So we add them here.
+  if (rgb_attrs.url >= 0) {
+    const char *url = hl_get_url((uint32_t)rgb_attrs.url);
+    PUT_C(rgb, "url", STRING_OBJ(cstr_as_string((char *)url)));
+  }
+
   ADD_C(args, DICTIONARY_OBJ(rgb));
   ADD_C(args, DICTIONARY_OBJ(cterm));
 
diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index e5a5cc059f..eea9b54a5c 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -176,6 +176,12 @@ void nvim_set_hl(Integer ns_id, String name, Dict(highlight) *val, Error *err)
   });
   int link_id = -1;
 
+  // Setting URLs directly through highlight attributes is not supported
+  if (HAS_KEY(val, highlight, url)) {
+    api_free_string(val->url);
+    val->url = NULL_STRING;
+  }
+
   HlAttrs attrs = dict2hlattrs(val, true, &link_id, err);
   if (!ERROR_SET(err)) {
     ns_hl_def((NS)ns_id, hl_id, attrs, link_id, val);
diff --git a/src/nvim/decoration.c b/src/nvim/decoration.c
index d3517c077f..7f1946ba05 100644
--- a/src/nvim/decoration.c
+++ b/src/nvim/decoration.c
@@ -118,7 +118,7 @@ void decor_redraw(buf_T *buf, int row1, int row2, DecorInline decor)
 
 void decor_redraw_sh(buf_T *buf, int row1, int row2, DecorSignHighlight sh)
 {
-  if (sh.hl_id || (sh.flags & (kSHIsSign|kSHSpellOn|kSHSpellOff))) {
+  if (sh.hl_id || (sh.url != NULL) || (sh.flags & (kSHIsSign|kSHSpellOn|kSHSpellOff))) {
     if (row2 >= row1) {
       redraw_buf_range_later(buf, row1 + 1, row2 + 1);
     }
@@ -253,7 +253,7 @@ void decor_free(DecorInline decor)
   }
 }
 
-void decor_free_inner(DecorVirtText *vt, uint32_t first_idx)
+static void decor_free_inner(DecorVirtText *vt, uint32_t first_idx)
 {
   while (vt) {
     if (vt->flags & kVTIsLines) {
@@ -273,6 +273,9 @@ void decor_free_inner(DecorVirtText *vt, uint32_t first_idx)
       xfree(sh->sign_name);
     }
     sh->flags = 0;
+    if (sh->url != NULL) {
+      XFREE_CLEAR(sh->url);
+    }
     if (sh->next == DECOR_ID_INVALID) {
       sh->next = decor_freelist;
       decor_freelist = first_idx;
@@ -509,7 +512,8 @@ void decor_range_add_sh(DecorState *state, int start_row, int start_col, int end
     .draw_col = -10,
   };
 
-  if (sh->hl_id || (sh->flags & (kSHConceal | kSHSpellOn | kSHSpellOff))) {
+  if (sh->hl_id || (sh->url != NULL)
+      || (sh->flags & (kSHConceal | kSHSpellOn | kSHSpellOff))) {
     if (sh->hl_id) {
       range.attr_id = syn_id2attr(sh->hl_id);
     }
@@ -627,15 +631,22 @@ next_mark:
         spell = kFalse;
       }
     }
+    if (active && item.data.sh.url != NULL) {
+      attr = hl_add_url(attr, item.data.sh.url);
+    }
     if (item.start_row == state->row && item.start_col <= col
         && decor_virt_pos(&item) && item.draw_col == -10) {
       decor_init_draw_col(win_col, hidden, &item);
     }
     if (keep) {
       kv_A(state->active, j++) = item;
-    } else if (item.owned && item.kind == kDecorKindVirtText) {
-      clear_virttext(&item.data.vt->data.virt_text);
-      xfree(item.data.vt);
+    } else if (item.owned) {
+      if (item.kind == kDecorKindVirtText) {
+        clear_virttext(&item.data.vt->data.virt_text);
+        xfree(item.data.vt);
+      } else if (item.kind == kDecorKindHighlight) {
+        xfree((void *)item.data.sh.url);
+      }
     }
   }
   kv_size(state->active) = j;
@@ -962,6 +973,10 @@ void decor_to_dict_legacy(Dictionary *dict, DecorInline decor, bool hl_name)
     PUT(*dict, "ui_watched", BOOLEAN_OBJ(true));
   }
 
+  if (sh_hl.url != NULL) {
+    PUT(*dict, "url", STRING_OBJ(cstr_to_string(sh_hl.url)));
+  }
+
   if (virt_text) {
     if (virt_text->hl_mode) {
       PUT(*dict, "hl_mode", CSTR_TO_OBJ(hl_mode_str[virt_text->hl_mode]));
diff --git a/src/nvim/decoration_defs.h b/src/nvim/decoration_defs.h
index 93bc202b94..8d0075b169 100644
--- a/src/nvim/decoration_defs.h
+++ b/src/nvim/decoration_defs.h
@@ -3,6 +3,7 @@
 #include <stdint.h>
 
 #include "klib/kvec.h"
+#include "nvim/api/private/defs.h"
 #include "nvim/types_defs.h"
 
 #define DECOR_ID_INVALID UINT32_MAX
@@ -68,10 +69,11 @@ typedef struct {
   int line_hl_id;
   int cursorline_hl_id;
   uint32_t next;
+  const char *url;
 } DecorSignHighlight;
 
 #define DECOR_SIGN_HIGHLIGHT_INIT { 0, DECOR_PRIORITY_BASE, 0, { 0, 0 }, NULL, 0, 0, 0, 0, \
-                                    DECOR_ID_INVALID }
+                                    DECOR_ID_INVALID, NULL }
 
 enum {
   kVTIsLines = 1,
diff --git a/src/nvim/highlight.c b/src/nvim/highlight.c
index bd599d686f..47a87b90c3 100644
--- a/src/nvim/highlight.c
+++ b/src/nvim/highlight.c
@@ -42,6 +42,7 @@ static Set(HlEntry) attr_entries = SET_INIT;
 static Map(int, int) combine_attr_entries = MAP_INIT;
 static Map(int, int) blend_attr_entries = MAP_INIT;
 static Map(int, int) blendthrough_attr_entries = MAP_INIT;
+static Set(cstr_t) urls = SET_INIT;
 
 #define attr_entry(i) attr_entries.keys[i]
 
@@ -475,6 +476,7 @@ int hl_get_underline(void)
       .rgb_bg_color = -1,
       .rgb_sp_color = -1,
       .hl_blend = -1,
+      .url = -1,
     },
     .kind = kHlUI,
     .id1 = 0,
@@ -482,6 +484,43 @@ int hl_get_underline(void)
   });
 }
 
+/// Augment an existing attribute with the beginning or end of a URL hyperlink.
+///
+/// @param attr Existing attribute to combine with
+/// @param url The URL to associate with the highlight attribute
+/// @return Combined attribute
+int hl_add_url(int attr, const char *url)
+{
+  HlAttrs attrs = HLATTRS_INIT;
+
+  MHPutStatus status;
+  uint32_t k = set_put_idx(cstr_t, &urls, url, &status);
+  if (status != kMHExisting) {
+    urls.keys[k] = xstrdup(url);
+  }
+
+  attrs.url = (int32_t)k;
+
+  int new = get_attr_entry((HlEntry){
+    .attr = attrs,
+    .kind = kHlUI,
+    .id1 = 0,
+    .id2 = 0,
+  });
+
+  return hl_combine_attr(attr, new);
+}
+
+/// Get a URL by its index.
+///
+/// @param index URL index
+/// @return URL
+const char *hl_get_url(uint32_t index)
+{
+  assert(urls.keys);
+  return urls.keys[index];
+}
+
 /// Get attribute code for forwarded :terminal highlights.
 int hl_get_term_attr(HlAttrs *aep)
 {
@@ -492,12 +531,18 @@ int hl_get_term_attr(HlAttrs *aep)
 /// Clear all highlight tables.
 void clear_hl_tables(bool reinit)
 {
+  const char *url = NULL;
+  set_foreach(&urls, url, {
+    xfree((void *)url);
+  });
+
   if (reinit) {
     set_clear(HlEntry, &attr_entries);
     highlight_init();
     map_clear(int, &combine_attr_entries);
     map_clear(int, &blend_attr_entries);
     map_clear(int, &blendthrough_attr_entries);
+    set_clear(cstr_t, &urls);
     memset(highlight_attr_last, -1, sizeof(highlight_attr_last));
     highlight_attr_set_all();
     highlight_changed();
@@ -508,6 +553,7 @@ void clear_hl_tables(bool reinit)
     map_destroy(int, &blend_attr_entries);
     map_destroy(int, &blendthrough_attr_entries);
     map_destroy(ColorKey, &ns_hls);
+    set_destroy(cstr_t, &urls);
   }
 }
 
@@ -599,6 +645,11 @@ int hl_combine_attr(int char_attr, int prim_attr)
     new_en.hl_blend = prim_aep.hl_blend;
   }
 
+  if ((new_en.url == -1) && (prim_aep.url >= 0)) {
+    // Combined attributes borrow the string from the primary attribute
+    new_en.url = prim_aep.url;
+  }
+
   id = get_attr_entry((HlEntry){ .attr = new_en, .kind = kHlCombine,
                                  .id1 = char_attr, .id2 = prim_attr });
   if (id > 0) {
@@ -680,8 +731,8 @@ int hl_blend_attrs(int back_attr, int front_attr, bool *through)
     }
 
     cattrs.cterm_bg_color = fattrs.cterm_bg_color;
-    cattrs.cterm_fg_color = cterm_blend(ratio, battrs.cterm_fg_color,
-                                        fattrs.cterm_bg_color);
+    cattrs.cterm_fg_color = (int16_t)cterm_blend(ratio, battrs.cterm_fg_color,
+                                                 fattrs.cterm_bg_color);
     cattrs.rgb_ae_attr &= ~(HL_FG_INDEXED | HL_BG_INDEXED);
   } else {
     cattrs = fattrs;
@@ -729,7 +780,7 @@ static int rgb_blend(int ratio, int rgb1, int rgb2)
   return (mr << 16) + (mg << 8) + mb;
 }
 
-static int cterm_blend(int ratio, int c1, int c2)
+static int cterm_blend(int ratio, int16_t c1, int16_t c2)
 {
   // 1. Convert cterm color numbers to RGB.
   // 2. Blend the RGB colors.
@@ -1085,12 +1136,12 @@ HlAttrs dict2hlattrs(Dict(highlight) *dict, bool use_rgb, int *link_id, Error *e
     hlattrs.rgb_fg_color = fg;
     hlattrs.rgb_sp_color = sp;
     hlattrs.hl_blend = blend;
-    hlattrs.cterm_bg_color = ctermbg == -1 ? 0 : ctermbg + 1;
-    hlattrs.cterm_fg_color = ctermfg == -1 ? 0 : ctermfg + 1;
+    hlattrs.cterm_bg_color = ctermbg == -1 ? 0 : (int16_t)(ctermbg + 1);
+    hlattrs.cterm_fg_color = ctermfg == -1 ? 0 : (int16_t)(ctermfg + 1);
     hlattrs.cterm_ae_attr = cterm_mask;
   } else {
-    hlattrs.cterm_bg_color = bg == -1 ? 0 : bg + 1;
-    hlattrs.cterm_fg_color = fg == -1 ? 0 : fg + 1;
+    hlattrs.cterm_bg_color = bg == -1 ? 0 : (int16_t)(bg + 1);
+    hlattrs.cterm_fg_color = fg == -1 ? 0 : (int16_t)(fg + 1);
     hlattrs.cterm_ae_attr = mask;
   }
 
diff --git a/src/nvim/highlight_defs.h b/src/nvim/highlight_defs.h
index 7a10e16391..25ab9dc2d9 100644
--- a/src/nvim/highlight_defs.h
+++ b/src/nvim/highlight_defs.h
@@ -3,6 +3,8 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#include "nvim/api/private/defs.h"
+
 typedef int32_t RgbValue;
 
 /// Highlighting attribute bits.
@@ -36,8 +38,9 @@ typedef enum {
 typedef struct {
   int16_t rgb_ae_attr, cterm_ae_attr;  ///< HlAttrFlags
   RgbValue rgb_fg_color, rgb_bg_color, rgb_sp_color;
-  int cterm_fg_color, cterm_bg_color;
-  int hl_blend;
+  int16_t cterm_fg_color, cterm_bg_color;
+  int32_t hl_blend;
+  int32_t url;
 } HlAttrs;
 
 #define HLATTRS_INIT (HlAttrs) { \
@@ -49,6 +52,7 @@ typedef struct {
   .cterm_fg_color = 0, \
   .cterm_bg_color = 0, \
   .hl_blend = -1, \
+  .url = -1, \
 }
 
 /// Values for index in highlight_attr[].
diff --git a/src/nvim/highlight_group.c b/src/nvim/highlight_group.c
index 14c44b0249..ef8181a4cb 100644
--- a/src/nvim/highlight_group.c
+++ b/src/nvim/highlight_group.c
@@ -1912,8 +1912,8 @@ static void set_hl_attr(int idx)
   HlGroup *sgp = hl_table + idx;
 
   at_en.cterm_ae_attr = (int16_t)sgp->sg_cterm;
-  at_en.cterm_fg_color = sgp->sg_cterm_fg;
-  at_en.cterm_bg_color = sgp->sg_cterm_bg;
+  at_en.cterm_fg_color = (int16_t)sgp->sg_cterm_fg;
+  at_en.cterm_bg_color = (int16_t)sgp->sg_cterm_bg;
   at_en.rgb_ae_attr = (int16_t)sgp->sg_gui;
   // FIXME(tarruda): The "unset value" for rgb is -1, but since hlgroup is
   // initialized with 0(by garray functions), check for sg_rgb_{f,b}g_name
diff --git a/src/nvim/map_defs.h b/src/nvim/map_defs.h
index f3c4e4ea95..836b1447c2 100644
--- a/src/nvim/map_defs.h
+++ b/src/nvim/map_defs.h
@@ -33,7 +33,8 @@ static inline bool equal_String(String a, String b)
   if (a.size != b.size) {
     return false;
   }
-  return memcmp(a.data, b.data, a.size) == 0;
+
+  return (a.size == 0) || (memcmp(a.data, b.data, a.size) == 0);
 }
 
 #define Set(type) Set_##type
diff --git a/src/nvim/terminal.c b/src/nvim/terminal.c
index 8bee5071af..00acbfb602 100644
--- a/src/nvim/terminal.c
+++ b/src/nvim/terminal.c
@@ -913,8 +913,8 @@ void terminal_get_line_attributes(Terminal *term, win_T *wp, int linenr, int *te
     bool fg_indexed = VTERM_COLOR_IS_INDEXED(&cell.fg);
     bool bg_indexed = VTERM_COLOR_IS_INDEXED(&cell.bg);
 
-    int vt_fg_idx = ((!fg_default && fg_indexed) ? cell.fg.indexed.idx + 1 : 0);
-    int vt_bg_idx = ((!bg_default && bg_indexed) ? cell.bg.indexed.idx + 1 : 0);
+    int16_t vt_fg_idx = ((!fg_default && fg_indexed) ? cell.fg.indexed.idx + 1 : 0);
+    int16_t vt_bg_idx = ((!bg_default && bg_indexed) ? cell.bg.indexed.idx + 1 : 0);
 
     bool fg_set = vt_fg_idx && vt_fg_idx <= 16 && term->color_set[vt_fg_idx - 1];
     bool bg_set = vt_bg_idx && vt_bg_idx <= 16 && term->color_set[vt_bg_idx - 1];
@@ -939,6 +939,7 @@ void terminal_get_line_attributes(Terminal *term, win_T *wp, int linenr, int *te
         .rgb_bg_color = vt_bg,
         .rgb_sp_color = -1,
         .hl_blend = -1,
+        .url = -1,
       });
     }
 
diff --git a/src/nvim/tui/tui.c b/src/nvim/tui/tui.c
index f9560ce076..35867d6ce3 100644
--- a/src/nvim/tui/tui.c
+++ b/src/nvim/tui/tui.c
@@ -32,6 +32,7 @@
 #include "nvim/os/input.h"
 #include "nvim/os/os.h"
 #include "nvim/os/os_defs.h"
+#include "nvim/strings.h"
 #include "nvim/tui/input.h"
 #include "nvim/tui/terminfo.h"
 #include "nvim/tui/tui.h"
@@ -139,6 +140,8 @@ struct TUIData {
   int width;
   int height;
   bool rgb;
+  int url;  ///< Index of URL currently being printed, if any
+  StringBuilder urlbuf;  ///< Re-usable buffer for writing OSC 8 control sequences
 };
 
 static int got_winch = 0;
@@ -147,6 +150,8 @@ static bool cursor_style_enabled = false;
 # include "tui/tui.c.generated.h"
 #endif
 
+static Set(cstr_t) urls = SET_INIT;
+
 void tui_start(TUIData **tui_p, int *width, int *height, char **term, bool *rgb)
   FUNC_ATTR_NONNULL_ALL
 {
@@ -156,7 +161,9 @@ void tui_start(TUIData **tui_p, int *width, int *height, char **term, bool *rgb)
   tui->stopped = false;
   tui->seen_error_exit = 0;
   tui->loop = &main_loop;
+  tui->url = -1;
   kv_init(tui->invalid_regions);
+  kv_init(tui->urlbuf);
   signal_watcher_init(tui->loop, &tui->winch_handle, tui);
 
   // TODO(bfredl): zero hl is empty, send this explicitly?
@@ -412,7 +419,7 @@ static void terminfo_start(TUIData *tui)
 static void terminfo_stop(TUIData *tui)
 {
   // Destroy output stuff
-  tui_mode_change(tui, (String)STRING_INIT, SHAPE_IDX_N);
+  tui_mode_change(tui, NULL_STRING, SHAPE_IDX_N);
   tui_mouse_off(tui);
   unibi_out(tui, unibi_exit_attribute_mode);
   // Reset cursor to normal before exiting alternate screen.
@@ -423,7 +430,7 @@ static void terminfo_stop(TUIData *tui)
   tui_reset_key_encoding(tui);
 
   // May restore old title before exiting alternate screen.
-  tui_set_title(tui, (String)STRING_INIT);
+  tui_set_title(tui, NULL_STRING);
   if (ui_client_exit_status == 0) {
     ui_client_exit_status = tui->seen_error_exit;
   }
@@ -522,7 +529,15 @@ void tui_free_all_mem(TUIData *tui)
 {
   ugrid_free(&tui->grid);
   kv_destroy(tui->invalid_regions);
+
+  const char *url;
+  set_foreach(&urls, url, {
+    xfree((void *)url);
+  });
+  set_destroy(cstr_t, &urls);
+
   kv_destroy(tui->attrs);
+  kv_destroy(tui->urlbuf);
   xfree(tui->space_buf);
   xfree(tui->term);
   xfree(tui);
@@ -550,6 +565,10 @@ static bool attrs_differ(TUIData *tui, int id1, int id2, bool rgb)
   HlAttrs a1 = kv_A(tui->attrs, (size_t)id1);
   HlAttrs a2 = kv_A(tui->attrs, (size_t)id2);
 
+  if (a1.url != a2.url) {
+    return true;
+  }
+
   if (rgb) {
     return a1.rgb_fg_color != a2.rgb_fg_color
            || a1.rgb_bg_color != a2.rgb_bg_color
@@ -709,6 +728,19 @@ static void update_attrs(TUIData *tui, int attr_id)
     }
   }
 
+  if (tui->url != attrs.url) {
+    if (attrs.url >= 0) {
+      const char *url = urls.keys[attrs.url];
+      kv_size(tui->urlbuf) = 0;
+      kv_printf(tui->urlbuf, "\x1b]8;;%s\x1b\\", url);
+      out(tui, tui->urlbuf.items, kv_size(tui->urlbuf));
+    } else {
+      out(tui, S_LEN("\x1b]8;;\x1b\\"));
+    }
+
+    tui->url = attrs.url;
+  }
+
   tui->default_attr = fg == -1 && bg == -1
                       && !bold && !italic && !has_any_underline && !reverse && !standout
                       && !strikethrough;
@@ -785,6 +817,13 @@ static void cursor_goto(TUIData *tui, int row, int col)
   if (row == grid->row && col == grid->col) {
     return;
   }
+
+  // If an OSC 8 sequence is active terminate it before moving the cursor
+  if (tui->url >= 0) {
+    out(tui, S_LEN("\x1b]8;;\x1b\\"));
+    tui->url = -1;
+  }
+
   if (0 == row && 0 == col) {
     unibi_out(tui, unibi_cursor_home);
     ugrid_goto(grid, row, col);
@@ -1281,11 +1320,32 @@ void tui_grid_scroll(TUIData *tui, Integer g, Integer startrow, Integer endrow,
   }
 }
 
+/// Add a URL to be used in an OSC 8 hyperlink.
+///
+/// @param tui TUIData
+/// @param url URL to add
+/// @return Index of new URL, or -1 if URL is invalid
+int32_t tui_add_url(TUIData *tui, const char *url)
+  FUNC_ATTR_NONNULL_ARG(1)
+{
+  if (url == NULL) {
+    return -1;
+  }
+
+  MHPutStatus status;
+  uint32_t k = set_put_idx(cstr_t, &urls, url, &status);
+  if (status != kMHExisting) {
+    urls.keys[k] = xstrdup(url);
+  }
+  return (int32_t)k;
+}
+
 void tui_hl_attr_define(TUIData *tui, Integer id, HlAttrs attrs, HlAttrs cterm_attrs, Array info)
 {
   attrs.cterm_ae_attr = cterm_attrs.cterm_ae_attr;
   attrs.cterm_fg_color = cterm_attrs.cterm_fg_color;
   attrs.cterm_bg_color = cterm_attrs.cterm_bg_color;
+
   kv_a(tui->attrs, (size_t)id) = attrs;
 }
 
@@ -1302,11 +1362,11 @@ void tui_visual_bell(TUIData *tui)
 void tui_default_colors_set(TUIData *tui, Integer rgb_fg, Integer rgb_bg, Integer rgb_sp,
                             Integer cterm_fg, Integer cterm_bg)
 {
-  tui->clear_attrs.rgb_fg_color = (int)rgb_fg;
-  tui->clear_attrs.rgb_bg_color = (int)rgb_bg;
-  tui->clear_attrs.rgb_sp_color = (int)rgb_sp;
-  tui->clear_attrs.cterm_fg_color = (int)cterm_fg;
-  tui->clear_attrs.cterm_bg_color = (int)cterm_bg;
+  tui->clear_attrs.rgb_fg_color = (RgbValue)rgb_fg;
+  tui->clear_attrs.rgb_bg_color = (RgbValue)rgb_bg;
+  tui->clear_attrs.rgb_sp_color = (RgbValue)rgb_sp;
+  tui->clear_attrs.cterm_fg_color = (int16_t)cterm_fg;
+  tui->clear_attrs.cterm_bg_color = (int16_t)cterm_bg;
 
   tui->print_attr_id = -1;
   invalidate(tui, 0, tui->grid.height, 0, tui->grid.width);
diff --git a/src/nvim/ui_client.c b/src/nvim/ui_client.c
index 055e234d67..d4dec7db83 100644
--- a/src/nvim/ui_client.c
+++ b/src/nvim/ui_client.c
@@ -175,7 +175,14 @@ static HlAttrs ui_client_dict2hlattrs(Dictionary d, bool rgb)
     // TODO(bfredl): log "err"
     return HLATTRS_INIT;
   }
-  return dict2hlattrs(&dict, rgb, NULL, &err);
+
+  HlAttrs attrs = dict2hlattrs(&dict, rgb, NULL, &err);
+
+  if (HAS_KEY(&dict, highlight, url)) {
+    attrs.url = tui_add_url(tui, dict.url.data);
+  }
+
+  return attrs;
 }
 
 void ui_client_event_grid_resize(Array args)
diff --git a/test/functional/api/extmark_spec.lua b/test/functional/api/extmark_spec.lua
index cb16f49e7c..0a286965f2 100644
--- a/test/functional/api/extmark_spec.lua
+++ b/test/functional/api/extmark_spec.lua
@@ -1791,6 +1791,13 @@ describe('API/extmarks', function()
     feed('vj2ed')
     eq({}, get_extmark_by_id(ns, 4, {}))
   end)
+
+  it('can set a URL', function()
+    set_extmark(ns, 1, 0, 0, { url = 'https://example.com', end_col = 3 })
+    local extmarks = get_extmarks(ns, 0, -1, { details = true })
+    eq(1, #extmarks)
+    eq('https://example.com', extmarks[1][4].url)
+  end)
 end)
 
 describe('Extmarks buffer api with many marks', function()
diff --git a/test/functional/terminal/tui_spec.lua b/test/functional/terminal/tui_spec.lua
index 46d3c98e07..5bfc7efbb3 100644
--- a/test/functional/terminal/tui_spec.lua
+++ b/test/functional/terminal/tui_spec.lua
@@ -1889,6 +1889,37 @@ describe('TUI', function()
       {3:-- TERMINAL --}                                    |
     ]])
   end)
+
+  it('emits hyperlinks with OSC 8', function()
+    exec_lua([[
+      local buf = vim.api.nvim_get_current_buf()
+      _G.urls = {}
+      vim.api.nvim_create_autocmd('TermRequest', {
+        buffer = buf,
+        callback = function(args)
+          local req = args.data
+          if not req then
+            return
+          end
+          local url = req:match('\027]8;;(.*)$')
+          if url ~= nil then
+            table.insert(_G.urls, url)
+          end
+        end,
+      })
+    ]])
+    child_exec_lua([[
+      vim.api.nvim_buf_set_lines(0, 0, 0, true, {'Hello'})
+      local ns = vim.api.nvim_create_namespace('test')
+      vim.api.nvim_buf_set_extmark(0, ns, 0, 1, {
+        end_col = 3,
+        url = 'https://example.com',
+      })
+    ]])
+    retry(nil, 1000, function()
+      eq({ 'https://example.com', '' }, exec_lua([[return _G.urls]]))
+    end)
+  end)
 end)
 
 describe('TUI', function()
diff --git a/test/functional/ui/decorations_spec.lua b/test/functional/ui/decorations_spec.lua
index 1b3d4afd5f..7b3533454c 100644
--- a/test/functional/ui/decorations_spec.lua
+++ b/test/functional/ui/decorations_spec.lua
@@ -2205,6 +2205,41 @@ describe('extmark decorations', function()
                                               |
     ]]}
   end)
+
+  it('supports URLs', function()
+    insert(example_text)
+
+    local url = 'https://example.com'
+
+    local attrs = screen:get_default_attr_ids()
+    table.insert(attrs, {
+      url = url,
+    })
+    screen:set_default_attr_ids(attrs)
+
+    api.nvim_buf_set_extmark(0, ns, 1, 4, {
+      end_col = 14,
+      url = url,
+    })
+
+    screen:expect{grid=[[
+      for _,item in ipairs(items) do                    |
+          {44:local text}, hl_id_cell, count = unpack(item)  |
+          if hl_id_cell ~= nil then                     |
+              hl_id = hl_id_cell                        |
+          end                                           |
+          for _ = 1, (count or 1) do                    |
+              local cell = line[colpos]                 |
+              cell.text = text                          |
+              cell.hl_id = hl_id                        |
+              colpos = colpos+1                         |
+          end                                           |
+      en^d                                               |
+      {1:~                                                 }|
+      {1:~                                                 }|
+                                                        |
+    ]]}
+  end)
 end)
 
 describe('decorations: inline virtual text', function()
diff --git a/test/functional/ui/screen.lua b/test/functional/ui/screen.lua
index a02130276d..3043a3c60a 100644
--- a/test/functional/ui/screen.lua
+++ b/test/functional/ui/screen.lua
@@ -1890,6 +1890,7 @@ function Screen:_equal_attrs(a, b)
     and a.strikethrough == b.strikethrough
     and a.fg_indexed == b.fg_indexed
     and a.bg_indexed == b.bg_indexed
+    and a.url == b.url
 end
 
 function Screen:_equal_info(a, b)